/* * Copyright (C) 2004 - 2005 Tomasz Kojm <tkojm@clamav.net> * * With additions from aCaB <acab@clamav.net> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #if HAVE_CONFIG_H #include "clamav-config.h" #endif #include <stdio.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/stat.h> #include <unistd.h> #include <time.h> #include "cltypes.h" #include "clamav.h" #include "others.h" #include "pe.h" #include "upx.h" #include "petite.h" #include "fsg.h" #include "spin.h" #include "scanners.h" #include "rebuildpe.h" #include "str.h" #include "execs.h" #define IMAGE_DOS_SIGNATURE 0x5a4d /* MZ */ #define IMAGE_DOS_SIGNATURE_OLD 0x4d5a /* ZM */ #define IMAGE_NT_SIGNATURE 0x00004550 #define IMAGE_OPTIONAL_SIGNATURE 0x010b #define DETECT_BROKEN (options & CL_SCAN_BLOCKBROKEN) #define BLOCKMAX (options & CL_SCAN_BLOCKMAX) #define UPX_NRV2B "\x11\xdb\x11\xc9\x01\xdb\x75\x07\x8b\x1e\x83\xee\xfc\x11\xdb\x11\xc9\x11\xc9\x75\x20\x41\x01\xdb" #define UPX_NRV2D "\x83\xf0\xff\x74\x78\xd1\xf8\x89\xc5\xeb\x0b\x01\xdb\x75\x07\x8b\x1e\x83\xee\xfc\x11\xdb\x11\xc9" #define UPX_NRV2E "\xeb\x52\x31\xc9\x83\xe8\x03\x72\x11\xc1\xe0\x08\x8a\x06\x46\x83\xf0\xff\x74\x75\xd1\xf8\x89\xc5" #if WORDS_BIGENDIAN == 0 #define EC16(v) (v) #define EC32(v) (v) #else static inline uint16_t EC16(uint16_t v) { return ((v >> 8) + (v << 8)); } static inline uint32_t EC32(uint32_t v) { return ((v >> 24) | ((v & 0x00FF0000) >> 8) | ((v & 0x0000FF00) << 8) | (v << 24)); } #endif extern short cli_leavetemps_flag; static uint32_t cli_rawaddr(uint32_t rva, struct pe_image_section_hdr *shp, uint16_t nos, unsigned int *err) { int i, found = 0; for(i = 0; i < nos; i++) { if(EC32(shp[i].VirtualAddress) <= rva && EC32(shp[i].VirtualAddress) + EC32(shp[i].SizeOfRawData) > rva) { found = 1; break; } } if(!found) { cli_dbgmsg("Can't calculate raw address from RVA 0x%x\n", rva); *err = 1; return 0; } *err = 0; return rva - EC32(shp[i].VirtualAddress) + EC32(shp[i].PointerToRawData); } /* static int cli_ddump(int desc, int offset, int size, const char *file) { int pos, ndesc, bread, sum = 0; char buff[FILEBUFF]; cli_dbgmsg("in ddump()\n"); if((pos = lseek(desc, 0, SEEK_CUR)) == -1) { cli_dbgmsg("Invalid descriptor\n"); return -1; } if(lseek(desc, offset, SEEK_SET) == -1) { cli_dbgmsg("lseek() failed\n"); lseek(desc, pos, SEEK_SET); return -1; } if((ndesc = open(file, O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU)) < 0) { cli_dbgmsg("Can't create file %s\n", file); lseek(desc, pos, SEEK_SET); return -1; } while((bread = read(desc, buff, FILEBUFF)) > 0) { if(sum + bread >= size) { if(write(ndesc, buff, size - sum) == -1) { cli_dbgmsg("Can't write to file\n"); lseek(desc, pos, SEEK_SET); close(ndesc); unlink(file); return -1; } break; } else { if(write(ndesc, buff, bread) == -1) { cli_dbgmsg("Can't write to file\n"); lseek(desc, pos, SEEK_SET); close(ndesc); unlink(file); return -1; } } sum += bread; } close(ndesc); lseek(desc, pos, SEEK_SET); return 0; } */ int cli_scanpe(int desc, const char **virname, long int *scanned, const struct cl_engine *engine, const struct cl_limits *limits, unsigned int options, unsigned int arec, unsigned int mrec) { uint16_t e_magic; /* DOS signature ("MZ") */ uint16_t nsections; uint32_t e_lfanew; /* address of new exe header */ uint32_t ep; /* entry point (raw) */ time_t timestamp; struct pe_image_file_hdr file_hdr; struct pe_image_optional_hdr optional_hdr; struct pe_image_section_hdr *section_hdr; struct stat sb; char sname[9], buff[4096], *tempfile; unsigned int i, found, upx_success = 0, min = 0, max = 0, err, broken = 0; unsigned int ssize = 0, dsize = 0, dll = 0; int (*upxfn)(char *, int , char *, int *, uint32_t, uint32_t, uint32_t) = NULL; char *src = NULL, *dest = NULL; int ndesc, ret; if(read(desc, &e_magic, sizeof(e_magic)) != sizeof(e_magic)) { cli_dbgmsg("Can't read DOS signature\n"); return CL_CLEAN; } if(EC16(e_magic) != IMAGE_DOS_SIGNATURE && EC16(e_magic) != IMAGE_DOS_SIGNATURE_OLD) { cli_dbgmsg("Invalid DOS signature\n"); return CL_CLEAN; } lseek(desc, 58, SEEK_CUR); /* skip to the end of the DOS header */ if(read(desc, &e_lfanew, sizeof(e_lfanew)) != sizeof(e_lfanew)) { cli_dbgmsg("Can't read new header address\n"); /* truncated header? */ if(DETECT_BROKEN) { if(virname) *virname = "Broken.Executable"; return CL_VIRUS; } return CL_CLEAN; } e_lfanew = EC32(e_lfanew); cli_dbgmsg("e_lfanew == %d\n", e_lfanew); if(!e_lfanew) { cli_dbgmsg("Not a PE file\n"); return CL_CLEAN; } if(lseek(desc, e_lfanew, SEEK_SET) < 0) { /* probably not a PE file */ cli_dbgmsg("Can't lseek to e_lfanew\n"); return CL_CLEAN; } if(read(desc, &file_hdr, sizeof(struct pe_image_file_hdr)) != sizeof(struct pe_image_file_hdr)) { /* bad information in e_lfanew - probably not a PE file */ cli_dbgmsg("Can't read file header\n"); return CL_CLEAN; } if(EC32(file_hdr.Magic) != IMAGE_NT_SIGNATURE) { cli_dbgmsg("Invalid PE signature (probably NE file)\n"); return CL_CLEAN; } if(EC16(file_hdr.Characteristics) & 0x2000) { cli_dbgmsg("File type: DLL\n"); dll = 1; } else if(EC16(file_hdr.Characteristics) & 0x01) { cli_dbgmsg("File type: Executable\n"); } switch(EC16(file_hdr.Machine)) { case 0x0: cli_dbgmsg("Machine type: Unknown\n"); case 0x14c: cli_dbgmsg("Machine type: 80386\n"); break; case 0x14d: cli_dbgmsg("Machine type: 80486\n"); break; case 0x14e: cli_dbgmsg("Machine type: 80586\n"); break; case 0x160: cli_dbgmsg("Machine type: R30000 (big-endian)\n"); break; case 0x162: cli_dbgmsg("Machine type: R3000\n"); break; case 0x166: cli_dbgmsg("Machine type: R4000\n"); break; case 0x168: cli_dbgmsg("Machine type: R10000\n"); break; case 0x184: cli_dbgmsg("Machine type: DEC Alpha AXP\n"); break; case 0x284: cli_dbgmsg("Machine type: DEC Alpha AXP 64bit\n"); break; case 0x1f0: cli_dbgmsg("Machine type: PowerPC\n"); break; case 0x200: cli_dbgmsg("Machine type: IA64\n"); break; case 0x268: cli_dbgmsg("Machine type: M68k\n"); break; case 0x266: cli_dbgmsg("Machine type: MIPS16\n"); break; case 0x366: cli_dbgmsg("Machine type: MIPS+FPU\n"); break; case 0x466: cli_dbgmsg("Machine type: MIPS16+FPU\n"); break; case 0x1a2: cli_dbgmsg("Machine type: Hitachi SH3\n"); break; case 0x1a3: cli_dbgmsg("Machine type: Hitachi SH3-DSP\n"); break; case 0x1a4: cli_dbgmsg("Machine type: Hitachi SH3-E\n"); break; case 0x1a6: cli_dbgmsg("Machine type: Hitachi SH4\n"); break; case 0x1a8: cli_dbgmsg("Machine type: Hitachi SH5\n"); break; case 0x1c0: cli_dbgmsg("Machine type: ARM\n"); break; case 0x1c2: cli_dbgmsg("Machine type: THUMB\n"); break; case 0x1d3: cli_dbgmsg("Machine type: AM33\n"); break; case 0x520: cli_dbgmsg("Machine type: Infineon TriCore\n"); break; case 0xcef: cli_dbgmsg("Machine type: CEF\n"); break; case 0xebc: cli_dbgmsg("Machine type: EFI Byte Code\n"); break; case 0x9041: cli_dbgmsg("Machine type: M32R\n"); break; case 0xc0ee: cli_dbgmsg("Machine type: CEE\n"); break; case 0x8664: cli_dbgmsg("Machine type: AMD64\n"); break; default: cli_warnmsg("Unknown machine type in PE header (0x%x)\n", EC16(file_hdr.Machine)); } nsections = EC16(file_hdr.NumberOfSections); if(nsections < 1) { if(DETECT_BROKEN) { if(virname) *virname = "Broken.Executable"; return CL_VIRUS; } cli_warnmsg("PE file contains no sections\n"); return CL_CLEAN; } cli_dbgmsg("NumberOfSections: %d\n", nsections); timestamp = (time_t) EC32(file_hdr.TimeDateStamp); cli_dbgmsg("TimeDateStamp: %s", ctime(×tamp)); cli_dbgmsg("SizeOfOptionalHeader: %d\n", EC16(file_hdr.SizeOfOptionalHeader)); if(EC16(file_hdr.SizeOfOptionalHeader) != sizeof(struct pe_image_optional_hdr)) { cli_warnmsg("Broken PE header detected.\n"); if(DETECT_BROKEN) { if(virname) *virname = "Broken.Executable"; return CL_VIRUS; } return CL_CLEAN; } if(read(desc, &optional_hdr, sizeof(struct pe_image_optional_hdr)) != sizeof(struct pe_image_optional_hdr)) { cli_dbgmsg("Can't optional file header\n"); if(DETECT_BROKEN) { if(virname) *virname = "Broken.Executable"; return CL_VIRUS; } return CL_CLEAN; } cli_dbgmsg("MajorLinkerVersion: %d\n", optional_hdr.MajorLinkerVersion); cli_dbgmsg("MinorLinkerVersion: %d\n", optional_hdr.MinorLinkerVersion); cli_dbgmsg("SizeOfCode: %d\n", EC32(optional_hdr.SizeOfCode)); cli_dbgmsg("SizeOfInitializedData: %d\n", EC32(optional_hdr.SizeOfInitializedData)); cli_dbgmsg("SizeOfUninitializedData: %d\n", EC32(optional_hdr.SizeOfUninitializedData)); cli_dbgmsg("AddressOfEntryPoint: 0x%x\n", EC32(optional_hdr.AddressOfEntryPoint)); cli_dbgmsg("SectionAlignment: %d\n", EC32(optional_hdr.SectionAlignment)); cli_dbgmsg("FileAlignment: %d\n", EC32(optional_hdr.FileAlignment)); cli_dbgmsg("MajorSubsystemVersion: %d\n", EC16(optional_hdr.MajorSubsystemVersion)); cli_dbgmsg("MinorSubsystemVersion: %d\n", EC16(optional_hdr.MinorSubsystemVersion)); cli_dbgmsg("SizeOfImage: %d\n", EC32(optional_hdr.SizeOfImage)); cli_dbgmsg("SizeOfHeaders: %d\n", EC32(optional_hdr.SizeOfHeaders)); switch(EC16(optional_hdr.Subsystem)) { case 0: cli_dbgmsg("Subsystem: Unknown\n"); break; case 1: cli_dbgmsg("Subsystem: Native (a driver ?)\n"); break; case 2: cli_dbgmsg("Subsystem: Win32 GUI\n"); break; case 3: cli_dbgmsg("Subsystem: Win32 console\n"); break; case 5: cli_dbgmsg("Subsystem: OS/2 console\n"); break; case 7: cli_dbgmsg("Subsystem: POSIX console\n"); break; case 8: cli_dbgmsg("Subsystem: Native Win9x driver\n"); break; case 9: cli_dbgmsg("Subsystem: WinCE GUI\n"); break; case 10: cli_dbgmsg("Subsystem: EFI application\n"); break; case 11: cli_dbgmsg("Subsystem: EFI driver\n"); break; case 12: cli_dbgmsg("Subsystem: EFI runtime driver\n"); break; default: cli_warnmsg("Unknown subsystem in PE header (0x%x)\n", EC16(optional_hdr.Subsystem)); } cli_dbgmsg("NumberOfRvaAndSizes: %d\n", EC32(optional_hdr.NumberOfRvaAndSizes)); cli_dbgmsg("------------------------------------\n"); if(fstat(desc, &sb) == -1) { cli_dbgmsg("fstat failed\n"); return CL_EIO; } section_hdr = (struct pe_image_section_hdr *) cli_calloc(nsections, sizeof(struct pe_image_section_hdr)); if(!section_hdr) { cli_dbgmsg("Can't allocate memory for section headers\n"); return CL_EMEM; } for(i = 0; i < nsections; i++) { if(read(desc, §ion_hdr[i], sizeof(struct pe_image_section_hdr)) != sizeof(struct pe_image_section_hdr)) { cli_dbgmsg("Can't read section header\n"); cli_dbgmsg("Possibly broken PE file\n"); free(section_hdr); if(DETECT_BROKEN) { if(virname) *virname = "Broken.Executable"; return CL_VIRUS; } return CL_CLEAN; } strncpy(sname, section_hdr[i].Name, 8); sname[8] = 0; cli_dbgmsg("Section %d\n", i); cli_dbgmsg("Section name: %s\n", sname); cli_dbgmsg("VirtualSize: %d\n", EC32(section_hdr[i].VirtualSize)); cli_dbgmsg("VirtualAddress: 0x%x\n", EC32(section_hdr[i].VirtualAddress)); cli_dbgmsg("SizeOfRawData: %d\n", EC32(section_hdr[i].SizeOfRawData)); cli_dbgmsg("PointerToRawData: 0x%x (%d)\n", EC32(section_hdr[i].PointerToRawData), EC32(section_hdr[i].PointerToRawData)); if(EC32(section_hdr[i].Characteristics) & 0x20) { cli_dbgmsg("Section contains executable code\n"); if(EC32(section_hdr[i].VirtualSize) < EC32(section_hdr[i].SizeOfRawData)) { cli_dbgmsg("Section contains free space\n"); /* cli_dbgmsg("Dumping %d bytes\n", section_hdr.SizeOfRawData - section_hdr.VirtualSize); ddump(desc, section_hdr.PointerToRawData + section_hdr.VirtualSize, section_hdr.SizeOfRawData - section_hdr.VirtualSize, cli_gentemp(NULL)); */ } } if(EC32(section_hdr[i].Characteristics) & 0x20000000) cli_dbgmsg("Section's memory is executable\n"); if(EC32(section_hdr[i].Characteristics) & 0x80000000) cli_dbgmsg("Section's memory is writeable\n"); cli_dbgmsg("------------------------------------\n"); if(EC32(section_hdr[i].PointerToRawData) + EC32(section_hdr[i].SizeOfRawData) > (unsigned long int) sb.st_size) { cli_dbgmsg("Possibly broken PE file - Section %d out of file (Offset@ %d, Rsize %d, Total filesize %d)\n", i, EC32(section_hdr[i].PointerToRawData), EC32(section_hdr[i].SizeOfRawData), sb.st_size); if(DETECT_BROKEN) { if(virname) *virname = "Broken.Executable"; free(section_hdr); return CL_VIRUS; } broken = 1; } if(!i) { min = EC32(section_hdr[i].VirtualAddress); max = EC32(section_hdr[i].VirtualAddress) + EC32(section_hdr[i].SizeOfRawData); } else { if(EC32(section_hdr[i].VirtualAddress) < min) min = EC32(section_hdr[i].VirtualAddress); if(EC32(section_hdr[i].VirtualAddress) + EC32(section_hdr[i].SizeOfRawData) > max) max = EC32(section_hdr[i].VirtualAddress) + EC32(section_hdr[i].SizeOfRawData); } } if((ep = EC32(optional_hdr.AddressOfEntryPoint)) >= min && !(ep = cli_rawaddr(EC32(optional_hdr.AddressOfEntryPoint), section_hdr, nsections, &err)) && err) { cli_dbgmsg("Possibly broken PE file\n"); free(section_hdr); if(DETECT_BROKEN) { if(virname) *virname = "Broken.Executable"; return CL_VIRUS; } return CL_CLEAN; } cli_dbgmsg("EntryPoint offset: 0x%x (%d)\n", ep, ep); /* Attempt to detect some popular polymorphic viruses */ /* W32.Parite.B */ if(!dll && ep == EC32(section_hdr[nsections - 1].PointerToRawData)) { lseek(desc, ep, SEEK_SET); if(read(desc, buff, 4096) == 4096) { const char *pt = cli_memstr(buff, 4040, "\x47\x65\x74\x50\x72\x6f\x63\x41\x64\x64\x72\x65\x73\x73\x00", 15); if(pt) { uint32_t dw1, dw2; pt += 15; if(((dw1 = cli_readint32(pt)) ^ (dw2 = cli_readint32(pt + 4))) == 0x505a4f && ((dw1 = cli_readint32(pt + 8)) ^ (dw2 = cli_readint32(pt + 12))) == 0xffffb && ((dw1 = cli_readint32(pt + 16)) ^ (dw2 = cli_readint32(pt + 20))) == 0xb8) { *virname = "W32.Parite.B"; free(section_hdr); return CL_VIRUS; } } } } /* W32.Magistr.A/B */ if(!dll && (EC32(section_hdr[nsections - 1].Characteristics) & 0x80000000)) { uint32_t rsize, vsize; rsize = EC32(section_hdr[nsections - 1].SizeOfRawData); vsize = EC32(section_hdr[nsections - 1].VirtualSize); if(rsize >= 0x612c && vsize >= 0x612c && ((vsize & 0xff) == 0xec)) { int bw = rsize < 0x7000 ? rsize : 0x7000; lseek(desc, EC32(section_hdr[nsections - 1].PointerToRawData) + rsize - bw, SEEK_SET); if(read(desc, buff, 4096) == 4096) { if(cli_memstr(buff, 4091, "\xe8\x2c\x61\x00\x00", 5)) { *virname = "W32.Magistr.A"; free(section_hdr); return CL_VIRUS; } } } else if(rsize >= 0x7000 && vsize >= 0x7000 && ((vsize & 0xff) == 0xed)) { int bw = rsize < 0x8000 ? rsize : 0x8000; lseek(desc, EC32(section_hdr[nsections - 1].PointerToRawData) + rsize - bw, SEEK_SET); if(read(desc, buff, 4096) == 4096) { if(cli_memstr(buff, 4091, "\xe8\x04\x72\x00\x00", 5)) { *virname = "W32.Magistr.B"; free(section_hdr); return CL_VIRUS; } } } } if(broken) { free(section_hdr); return CL_CLEAN; } /* UPX & FSG support */ /* try to find the first section with physical size == 0 */ found = 0; for(i = 0; i < (unsigned int) nsections - 1; i++) { if(!section_hdr[i].SizeOfRawData && section_hdr[i].VirtualSize && section_hdr[i + 1].SizeOfRawData && section_hdr[i + 1].VirtualSize) { found = 1; cli_dbgmsg("UPX/FSG: empty section found - assuming compression\n"); break; } } if(found) { /* Check EP for UPX vs. FSG */ if(lseek(desc, ep, SEEK_SET) == -1) { cli_dbgmsg("UPX/FSG: lseek() failed\n"); free(section_hdr); return CL_EIO; } if(read(desc, buff, 168) != 168) { cli_dbgmsg("UPX/FSG: Can't read 168 bytes at 0x%x (%d)\n", ep, ep); cli_dbgmsg("UPX/FSG: Broken or not UPX/FSG compressed file\n"); free(section_hdr); return CL_CLEAN; } if(buff[0] == '\x87' && buff[1] == '\x25') { /* FSG v2.0 support - thanks to aCaB ! */ ssize = EC32(section_hdr[i + 1].SizeOfRawData); dsize = EC32(section_hdr[i].VirtualSize); while(found) { uint32_t newesi, newedi, newebx, newedx; if(limits && limits->maxfilesize && (ssize > limits->maxfilesize || dsize > limits->maxfilesize)) { cli_dbgmsg("FSG: Sizes exceeded (ssize: %d, dsize: %d, max: %lu)\n", ssize, dsize , limits->maxfilesize); free(section_hdr); if(BLOCKMAX) { *virname = "PE.FSG.ExceededFileSize"; return CL_VIRUS; } else { return CL_CLEAN; } } if(ssize <= 0x19 || dsize <= ssize) { cli_dbgmsg("FSG: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize); free(section_hdr); return CL_CLEAN; } if((newedx = cli_readint32(buff + 2) - EC32(optional_hdr.ImageBase)) < EC32(section_hdr[i + 1].VirtualAddress) || newedx >= EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData) - 4) { cli_dbgmsg("FSG: xchg out of bounds (%x), giving up\n", newedx); break; } if((src = (char *) cli_malloc(ssize)) == NULL) { free(section_hdr); return CL_EMEM; } lseek(desc, EC32(section_hdr[i + 1].PointerToRawData), SEEK_SET); if((unsigned int) read(desc, src, ssize) != ssize) { cli_dbgmsg("Can't read raw data of section %d\n", i); free(section_hdr); free(src); return CL_EIO; } if(newedx < EC32(section_hdr[i + 1].VirtualAddress) || ((dest = src + newedx - EC32(section_hdr[i + 1].VirtualAddress)) < src && dest >= src + EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData) - 4)) { cli_dbgmsg("FSG: New ESP out of bounds\n"); free(src); break; } if((newedx = cli_readint32(dest) - EC32(optional_hdr.ImageBase)) <= EC32(section_hdr[i + 1].VirtualAddress) || newedx >= EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData) - 4) { cli_dbgmsg("FSG: New ESP (%x) is wrong\n", newedx); free(src); break; } if((dest = src + newedx - EC32(section_hdr[i + 1].VirtualAddress)) < src || dest >= src + EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData) - 32) { cli_dbgmsg("FSG: New stack out of bounds\n"); free(src); break; } newedi = cli_readint32(dest) - EC32(optional_hdr.ImageBase); newesi = cli_readint32(dest + 4) - EC32(optional_hdr.ImageBase); newebx = cli_readint32(dest + 16) - EC32(optional_hdr.ImageBase); newedx = cli_readint32(dest + 20); if(newedi != EC32(section_hdr[i].VirtualAddress)) { cli_dbgmsg("FSG: Bad destination buffer (edi is %x should be %x)\n", newedi, EC32(section_hdr[i].VirtualAddress)); free(src); break; } if(newesi < EC32(section_hdr[i + 1].VirtualAddress) || newesi >= EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData)) { cli_dbgmsg("FSG: Source buffer out of section bounds\n"); free(src); break; } if(newebx < EC32(section_hdr[i + 1].VirtualAddress) || newebx >= EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData) - 16) { cli_dbgmsg("FSG: Array of functions out of bounds\n"); free(src); break; } newedx=cli_readint32(newebx + 12 - EC32(section_hdr[i + 1].VirtualAddress) + src) - EC32(optional_hdr.ImageBase); cli_dbgmsg("FSG: found old EP @%x\n",newedx); if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) { free(section_hdr); free(src); return CL_EMEM; } tempfile = cli_gentemp(NULL); if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) { cli_dbgmsg("FSG: Can't create file %s\n", tempfile); free(tempfile); free(section_hdr); free(src); free(dest); return CL_EIO; } switch (unfsg_200(newesi - EC32(section_hdr[i + 1].VirtualAddress) + src, dest, ssize + EC32(section_hdr[i + 1].VirtualAddress) - newesi, dsize, newedi, EC32(optional_hdr.ImageBase), newedx, ndesc)) { case 1: /* Everything OK */ cli_dbgmsg("FSG: Unpacked and rebuilt executable saved in %s\n", tempfile); free(src); free(dest); fsync(ndesc); lseek(ndesc, 0, SEEK_SET); cli_dbgmsg("***** Scanning rebuilt PE file *****\n"); if(cli_magic_scandesc(ndesc, virname, scanned, engine, limits, options, arec, mrec) == CL_VIRUS) { free(section_hdr); close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); return CL_VIRUS; } close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); free(section_hdr); return CL_CLEAN; case 0: /* We've got an unpacked buffer, no exe though */ cli_dbgmsg("FSG: FSG: Successfully decompressed\n"); close(ndesc); unlink(tempfile); free(tempfile); found = 0; upx_success = 1; break; /* Go and scan the buffer! */ default: /* Everything gone wrong */ cli_dbgmsg("FSG: Unpacking failed\n"); close(ndesc); unlink(tempfile); // It's empty anyway free(tempfile); free(src); free(dest); break; } break; /* were done with 2 */ } } if(found && buff[0] == '\xbe' && cli_readint32(buff + 1) - EC32(optional_hdr.ImageBase) < min) { /* FSG support - v. 1.33 (thx trog for the many samples) */ ssize = EC32(section_hdr[i + 1].SizeOfRawData); dsize = EC32(section_hdr[i].VirtualSize); while(found) { int gp, t, sectcnt = 0; char *support; uint32_t newesi, newedi, newebx, oldep; struct SECTION *sections; if(limits && limits->maxfilesize && (ssize > limits->maxfilesize || dsize > limits->maxfilesize)) { cli_dbgmsg("FSG: Sizes exceeded (ssize: %d, dsize: %d, max: %lu)\n", ssize, dsize, limits->maxfilesize); free(section_hdr); if(BLOCKMAX) { *virname = "PE.FSG.ExceededFileSize"; return CL_VIRUS; } else { return CL_CLEAN; } } if(ssize <= 0x19 || dsize <= ssize) { cli_dbgmsg("FSG: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize); free(section_hdr); return CL_CLEAN; } if((gp = cli_readint32(buff + 1) - EC32(optional_hdr.ImageBase)) >= (int) EC32(section_hdr[i + 1].PointerToRawData) || gp < 0) { cli_dbgmsg("FSG: Support data out of padding area (vaddr: %d)\n", EC32(section_hdr[i].VirtualAddress)); break; } lseek(desc, gp, SEEK_SET); gp = EC32(section_hdr[i + 1].PointerToRawData) - gp; if(limits && limits->maxfilesize && (unsigned int) gp > limits->maxfilesize) { cli_dbgmsg("FSG: Buffer size exceeded (size: %d, max: %lu)\n", gp, limits->maxfilesize); free(section_hdr); if(BLOCKMAX) { *virname = "PE.FSG.ExceededFileSize"; return CL_VIRUS; } else { return CL_CLEAN; } } if((support = (char *) cli_malloc(gp)) == NULL) { free(section_hdr); return CL_EMEM; } if(read(desc, support, gp) != gp) { cli_dbgmsg("Can't read %d bytes from padding area\n", gp); free(section_hdr); free(support); return CL_EIO; } newebx = cli_readint32(support) - EC32(optional_hdr.ImageBase); /* Unused */ newedi = cli_readint32(support + 4) - EC32(optional_hdr.ImageBase); /* 1st dest */ newesi = cli_readint32(support + 8) - EC32(optional_hdr.ImageBase); /* Source */ if(newesi < EC32(section_hdr[i + 1].VirtualAddress) || newesi >= EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData)) { cli_dbgmsg("FSG: Source buffer out of section bounds\n"); free(support); break; } if(newedi != EC32(section_hdr[i].VirtualAddress)) { cli_dbgmsg("FSG: Bad destination (is %x should be %x)\n", newedi, EC32(section_hdr[i].VirtualAddress)); free(support); break; } /* Counting original sections */ for(t = 12; t < gp - 4; t += 4) { uint32_t rva = cli_readint32(support+t); if(!rva) break; rva -= EC32(optional_hdr.ImageBase)+1; sectcnt++; if(rva % 0x1000) /* FIXME: really need to bother? */ cli_dbgmsg("FSG: Original section %d is misaligned\n", sectcnt); if(rva < EC32(section_hdr[i].VirtualAddress) || rva >= EC32(section_hdr[i].VirtualAddress)+EC32(section_hdr[i].VirtualSize)) { cli_dbgmsg("FSG: Original section %d is out of bounds\n", sectcnt); break; } } if(t >= gp - 4 || cli_readint32(support + t)) { free(support); break; } if((sections = (struct SECTION *) cli_malloc((sectcnt + 1) * sizeof(struct SECTION))) == NULL) { free(section_hdr); free(support); return CL_EMEM; } sections[0].rva = newedi; for(t = 1; t <= sectcnt; t++) sections[t].rva = cli_readint32(support + 8 + t * 4) - 1 -EC32(optional_hdr.ImageBase); free(support); if((src = (char *) cli_malloc(ssize)) == NULL) { free(section_hdr); free(sections); return CL_EMEM; } lseek(desc, EC32(section_hdr[i + 1].PointerToRawData), SEEK_SET); if((unsigned int) read(desc, src, ssize) != ssize) { cli_dbgmsg("Can't read raw data of section %d\n", i); free(section_hdr); free(sections); free(src); return CL_EIO; } if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) { free(section_hdr); free(src); free(sections); return CL_EMEM; } oldep = EC32(optional_hdr.AddressOfEntryPoint) + 161 + 6 + cli_readint32(buff+163); cli_dbgmsg("FSG: found old EP @%x\n", oldep); tempfile = cli_gentemp(NULL); if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) { cli_dbgmsg("FSG: Can't create file %s\n", tempfile); free(tempfile); free(section_hdr); free(src); free(dest); free(sections); return CL_EIO; } switch(unfsg_133(src + newesi - EC32(section_hdr[i + 1].VirtualAddress), dest, ssize + EC32(section_hdr[i + 1].VirtualAddress) - newesi, dsize, sections, sectcnt, EC32(optional_hdr.ImageBase), oldep, ndesc)) { case 1: /* Everything OK */ cli_dbgmsg("FSG: Unpacked and rebuilt executable saved in %s\n", tempfile); free(src); free(dest); free(sections); fsync(ndesc); lseek(ndesc, 0, SEEK_SET); cli_dbgmsg("***** Scanning rebuilt PE file *****\n"); if(cli_magic_scandesc(ndesc, virname, scanned, engine, limits, options, arec, mrec) == CL_VIRUS) { free(section_hdr); close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); return CL_VIRUS; } close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); free(section_hdr); return CL_CLEAN; case 0: /* We've got an unpacked buffer, no exe though */ cli_dbgmsg("FSG: FSG: Successfully decompressed\n"); close(ndesc); unlink(tempfile); free(tempfile); free(sections); found = 0; upx_success = 1; break; /* Go and scan the buffer! */ default: /* Everything gone wrong */ cli_dbgmsg("FSG: Unpacking failed\n"); close(ndesc); unlink(tempfile); // It's empty anyway free(tempfile); free(src); free(dest); free(sections); break; } break; /* were done with 1.33 */ } } /* FIXME: easy 2 hack */ if(found && buff[0] == '\xbb' && cli_readint32(buff + 1) - EC32(optional_hdr.ImageBase) < min && buff[5] == '\xbf' && buff[10] == '\xbe') { /* FSG support - v. 1.31 */ ssize = EC32(section_hdr[i + 1].SizeOfRawData); dsize = EC32(section_hdr[i].VirtualSize); while(found) { int gp = cli_readint32(buff+1) - EC32(optional_hdr.ImageBase), t, sectcnt = 0; char *support; uint32_t newesi = cli_readint32(buff+11) - EC32(optional_hdr.ImageBase); uint32_t newedi = cli_readint32(buff+6) - EC32(optional_hdr.ImageBase); uint32_t oldep = EC32(optional_hdr.AddressOfEntryPoint); struct SECTION *sections; if (oldep <= EC32(section_hdr[i + 1].VirtualAddress) || oldep > EC32(section_hdr[i + 1].VirtualAddress)+EC32(section_hdr[i + 1].SizeOfRawData) - 0xe0) { cli_dbgmsg("FSG: EP not in section %d\n", i+1); break; } oldep -= EC32(section_hdr[i + 1].VirtualAddress); if(newesi < EC32(section_hdr[i + 1].VirtualAddress) || newesi >= EC32(section_hdr[i + 1].VirtualAddress) + EC32(section_hdr[i + 1].SizeOfRawData)) { cli_dbgmsg("FSG: Source buffer out of section bounds\n"); break; } if(newedi != EC32(section_hdr[i].VirtualAddress)) { cli_dbgmsg("FSG: Bad destination (is %x should be %x)\n", newedi, EC32(section_hdr[i].VirtualAddress)); break; } if(limits && limits->maxfilesize && (ssize > limits->maxfilesize || dsize > limits->maxfilesize)) { cli_dbgmsg("FSG: Sizes exceeded (ssize: %d, dsize: %d, max: %lu)\n", ssize, dsize, limits->maxfilesize); free(section_hdr); if(BLOCKMAX) { *virname = "PE.FSG.ExceededFileSize"; return CL_VIRUS; } else { return CL_CLEAN; } } if(ssize <= 0x19 || dsize <= ssize) { cli_dbgmsg("FSG: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize); free(section_hdr); return CL_CLEAN; } if(gp >= (int) EC32(section_hdr[i + 1].PointerToRawData) || gp < 0) { cli_dbgmsg("FSG: Support data out of padding area (newedi: %d, vaddr: %d)\n", newedi, EC32(section_hdr[i].VirtualAddress)); break; } lseek(desc, gp, SEEK_SET); gp = EC32(section_hdr[i + 1].PointerToRawData) - gp; if(limits && limits->maxfilesize && (unsigned int) gp > limits->maxfilesize) { cli_dbgmsg("FSG: Buffer size exceeded (size: %d, max: %lu)\n", gp, limits->maxfilesize); free(section_hdr); if(BLOCKMAX) { *virname = "PE.FSG.ExceededFileSize"; return CL_VIRUS; } else { return CL_CLEAN; } } if((support = (char *) cli_malloc(gp)) == NULL) { free(section_hdr); return CL_EMEM; } if(read(desc, support, gp) != gp) { cli_dbgmsg("Can't read %d bytes from padding area\n", gp); free(section_hdr); free(support); return CL_EIO; } /* Counting original sections */ for(t = 0; t < gp - 2; t += 2) { uint32_t rva = support[t]+256*support[t+1]; if (rva == 2 || rva == 1) break; rva = ((rva-2)<<12) - EC32(optional_hdr.ImageBase); sectcnt++; if(rva < EC32(section_hdr[i].VirtualAddress) || rva >= EC32(section_hdr[i].VirtualAddress)+EC32(section_hdr[i].VirtualSize)) { cli_dbgmsg("FSG: Original section %d is out of bounds\n", sectcnt); break; } } if(t >= gp-10 || cli_readint32(support + t + 6) != 2) { free(support); break; } if((sections = (struct SECTION *) cli_malloc((sectcnt + 1) * sizeof(struct SECTION))) == NULL) { free(section_hdr); free(support); return CL_EMEM; } sections[0].rva = newedi; for(t = 0; t <= sectcnt - 1; t++) { sections[t+1].rva = (((support[t*2]+256*support[t*2+1])-2)<<12)-EC32(optional_hdr.ImageBase); } free(support); if((src = (char *) cli_malloc(ssize)) == NULL) { free(section_hdr); free(sections); return CL_EMEM; } lseek(desc, EC32(section_hdr[i + 1].PointerToRawData), SEEK_SET); if((unsigned int) read(desc, src, ssize) != ssize) { cli_dbgmsg("Can't read raw data of section %d\n", i); free(section_hdr); free(sections); free(src); return CL_EIO; } if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) { free(section_hdr); free(src); free(sections); return CL_EMEM; } /* Better not increasing buff size any further, let's go the hard way */ gp = 0xda + 6*(buff[16]=='\xe8'); oldep = EC32(optional_hdr.AddressOfEntryPoint) + gp + 6 + cli_readint32(src+gp+2+oldep); cli_dbgmsg("FSG: found old EP @%x\n", oldep); tempfile = cli_gentemp(NULL); if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) { cli_dbgmsg("FSG: Can't create file %s\n", tempfile); free(tempfile); free(section_hdr); free(src); free(dest); free(sections); return CL_EIO; } switch(unfsg_133(src + newesi - EC32(section_hdr[i + 1].VirtualAddress), dest, ssize + EC32(section_hdr[i + 1].VirtualAddress) - newesi, dsize, sections, sectcnt, EC32(optional_hdr.ImageBase), oldep, ndesc)) { case 1: /* Everything OK */ cli_dbgmsg("FSG: Unpacked and rebuilt executable saved in %s\n", tempfile); free(src); free(dest); free(sections); fsync(ndesc); lseek(ndesc, 0, SEEK_SET); cli_dbgmsg("***** Scanning rebuilt PE file *****\n"); if(cli_magic_scandesc(ndesc, virname, scanned, engine, limits, options, arec, mrec) == CL_VIRUS) { free(section_hdr); close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); return CL_VIRUS; } close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); free(section_hdr); return CL_CLEAN; case 0: /* We've got an unpacked buffer, no exe though */ cli_dbgmsg("FSG: FSG: Successfully decompressed\n"); close(ndesc); unlink(tempfile); free(tempfile); free(sections); found = 0; upx_success = 1; break; /* Go and scan the buffer! */ default: /* Everything gone wrong */ cli_dbgmsg("FSG: Unpacking failed\n"); close(ndesc); unlink(tempfile); // It's empty anyway free(tempfile); free(src); free(dest); free(sections); break; } break; /* were done with 1.31 */ } } if(found) { /* UPX support */ strncpy(sname, section_hdr[i].Name, 8); sname[8] = 0; cli_dbgmsg("UPX: Section %d name: %s\n", i, sname); strncpy(sname, section_hdr[i + 1].Name, 8); sname[8] = 0; cli_dbgmsg("UPX: Section %d name: %s\n", i + 1, sname); if(strncmp(section_hdr[i].Name, "UPX0", 4) || strncmp(section_hdr[i + 1].Name, "UPX1", 4)) cli_dbgmsg("UPX: Possibly hacked UPX section headers\n"); /* we assume (i + 1) is UPX1 */ ssize = EC32(section_hdr[i + 1].SizeOfRawData); dsize = EC32(section_hdr[i].VirtualSize) + EC32(section_hdr[i + 1].VirtualSize); if(limits && limits->maxfilesize && (ssize > limits->maxfilesize || dsize > limits->maxfilesize)) { cli_dbgmsg("UPX: Sizes exceeded (ssize: %d, dsize: %d, max: %lu)\n", ssize, dsize , limits->maxfilesize); free(section_hdr); if(BLOCKMAX) { *virname = "PE.UPX.ExceededFileSize"; return CL_VIRUS; } else { return CL_CLEAN; } } if(ssize <= 0x19 || dsize <= ssize) { /* FIXME: What are reasonable values? */ cli_dbgmsg("UPX: Size mismatch (ssize: %d, dsize: %d)\n", ssize, dsize); free(section_hdr); return CL_CLEAN; } /* FIXME: use file operations in case of big files */ if((src = (char *) cli_malloc(ssize)) == NULL) { free(section_hdr); return CL_EMEM; } if((dest = (char *) cli_calloc(dsize + 1024 + nsections * 40, sizeof(char))) == NULL) { free(section_hdr); free(src); return CL_EMEM; } lseek(desc, EC32(section_hdr[i + 1].PointerToRawData), SEEK_SET); if((unsigned int) read(desc, src, ssize) != ssize) { cli_dbgmsg("Can't read raw data of section %d\n", i); free(section_hdr); free(src); free(dest); return CL_EIO; } /* try to detect UPX code */ if(lseek(desc, ep, SEEK_SET) == -1) { cli_dbgmsg("lseek() failed\n"); free(section_hdr); free(src); free(dest); return CL_EIO; } if(read(desc, buff, 126) != 126) { /* i.e. 0x69 + 13 + 8 */ cli_dbgmsg("UPX: Can't read 126 bytes at 0x%x (%d)\n", ep, ep); cli_dbgmsg("UPX/FSG: Broken or not UPX/FSG compressed file\n"); free(section_hdr); free(src); free(dest); return CL_CLEAN; } else { if(cli_memstr(UPX_NRV2B, 24, buff + 0x69, 13) || cli_memstr(UPX_NRV2B, 24, buff + 0x69 + 8, 13)) { cli_dbgmsg("UPX: Looks like a NRV2B decompression routine\n"); upxfn = upx_inflate2b; } else if(cli_memstr(UPX_NRV2D, 24, buff + 0x69, 13) || cli_memstr(UPX_NRV2D, 24, buff + 0x69 + 8, 13)) { cli_dbgmsg("UPX: Looks like a NRV2D decompression routine\n"); upxfn = upx_inflate2d; } else if(cli_memstr(UPX_NRV2E, 24, buff + 0x69, 13) || cli_memstr(UPX_NRV2E, 24, buff + 0x69 + 8, 13)) { cli_dbgmsg("UPX: Looks like a NRV2E decompression routine\n"); upxfn = upx_inflate2e; } } if(upxfn) { int skew = cli_readint32(buff + 2) - EC32(optional_hdr.ImageBase) - EC32(section_hdr[i + 1].VirtualAddress); if(buff[1] != '\xbe' || skew <= 0 || skew > 0xfff) { /* FIXME: legit skews?? */ skew = 0; if(upxfn(src, ssize, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint)) >= 0) upx_success = 1; } else { cli_dbgmsg("UPX: UPX1 seems skewed by %d bytes\n", skew); if(upxfn(src + skew, ssize - skew, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint)-skew) >= 0 || upxfn(src, ssize, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint)) >= 0) upx_success = 1; } if(upx_success) cli_dbgmsg("UPX: Successfully decompressed\n"); else cli_dbgmsg("UPX: Prefered decompressor failed\n"); } if(!upx_success && upxfn != upx_inflate2b) { if(upx_inflate2b(src, ssize, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint)) == -1 && upx_inflate2b(src + 0x15, ssize - 0x15, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint) - 0x15) == -1) { cli_dbgmsg("UPX: NRV2B decompressor failed\n"); } else { upx_success = 1; cli_dbgmsg("UPX: Successfully decompressed with NRV2B\n"); } } if(!upx_success && upxfn != upx_inflate2d) { if(upx_inflate2d(src, ssize, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint)) == -1 && upx_inflate2d(src + 0x15, ssize - 0x15, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint) - 0x15) == -1) { cli_dbgmsg("UPX: NRV2D decompressor failed\n"); } else { upx_success = 1; cli_dbgmsg("UPX: Successfully decompressed with NRV2D\n"); } } if(!upx_success && upxfn != upx_inflate2e) { if(upx_inflate2e(src, ssize, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint)) == -1 && upx_inflate2e(src + 0x15, ssize - 0x15, dest, &dsize, EC32(section_hdr[i].VirtualAddress), EC32(section_hdr[i + 1].VirtualAddress), EC32(optional_hdr.AddressOfEntryPoint) - 0x15) == -1) { cli_dbgmsg("UPX: NRV2E decompressor failed\n"); } else { upx_success = 1; cli_dbgmsg("UPX: Successfully decompressed with NRV2E\n"); } } if(!upx_success) { cli_dbgmsg("UPX: All decompressors failed\n"); free(src); free(dest); } } if(upx_success) { free(src); free(section_hdr); tempfile = cli_gentemp(NULL); if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) { cli_dbgmsg("UPX/FSG: Can't create file %s\n", tempfile); free(tempfile); free(dest); return CL_EIO; } if((unsigned int) write(ndesc, dest, dsize) != dsize) { cli_dbgmsg("UPX/FSG: Can't write %d bytes\n", dsize); free(tempfile); free(dest); close(ndesc); return CL_EIO; } free(dest); fsync(ndesc); lseek(ndesc, 0, SEEK_SET); if(cli_leavetemps_flag) cli_dbgmsg("UPX/FSG: Decompressed data saved in %s\n", tempfile); cli_dbgmsg("***** Scanning decompressed file *****\n"); if((ret = cli_magic_scandesc(ndesc, virname, scanned, engine, limits, options, arec, mrec)) == CL_VIRUS) { close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); return CL_VIRUS; } close(ndesc); if(!cli_leavetemps_flag) unlink(tempfile); free(tempfile); return ret; } } /* Petite */ found = 2; lseek(desc, ep, SEEK_SET); if(read(desc, buff, 200) != 200) { cli_dbgmsg("Can't read 200 bytes\n"); free(section_hdr); return CL_EIO; } if(buff[0] != '\xb8' || (uint32_t) cli_readint32(buff + 1) != EC32(section_hdr[nsections - 1].VirtualAddress) + EC32(optional_hdr.ImageBase)) { if(nsections < 2 || buff[0] != '\xb8' || (uint32_t) cli_readint32(buff + 1) != EC32(section_hdr[nsections - 2].VirtualAddress) + EC32(optional_hdr.ImageBase)) found = 0; else found = 1; } if(found) { cli_dbgmsg("Petite: v2.%d compression detected\n", found); if(cli_readint32(buff + 0x80) == 0x163c988d) { cli_dbgmsg("Petite: level zero compression is not supported yet\n"); } else { dsize = max - min; if(limits && limits->maxfilesize && dsize > limits->maxfilesize) { cli_dbgmsg("Petite: Size exceeded (dsize: %d, max: %lu)\n", dsize, limits->maxfilesize); free(section_hdr); if(BLOCKMAX) { *virname = "PE.Petite.ExceededFileSize"; return CL_VIRUS; } else { return CL_CLEAN; } } if((dest = (char *) cli_calloc(dsize, sizeof(char))) == NULL) { cli_dbgmsg("Petite: Can't allocate %d bytes\n", dsize); free(section_hdr); return CL_EMEM; } for(i = 0 ; i < nsections; i++) { if(section_hdr[i].SizeOfRawData) { uint32_t offset = cli_rawaddr(EC32(section_hdr[i].VirtualAddress), section_hdr, nsections, &err); if(err || lseek(desc, offset, SEEK_SET) == -1 || (unsigned int) read(desc, dest + EC32(section_hdr[i].VirtualAddress) - min, EC32(section_hdr[i].SizeOfRawData)) != EC32(section_hdr[i].SizeOfRawData)) { free(section_hdr); free(dest); return CL_EIO; } } } tempfile = cli_gentemp(NULL); if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) { cli_dbgmsg("Petite: Can't create file %s\n", tempfile); free(tempfile); free(section_hdr); free(dest); return CL_EIO; } /* aCaB: Fixed to allow petite v2.1 unpacking (last section is a ghost) */ switch(petite_inflate2x_1to9(dest, min, max - min, section_hdr, nsections - (found == 1 ? 1 : 0), EC32(optional_hdr.ImageBase), EC32(optional_hdr.AddressOfEntryPoint), ndesc, found, EC32(optional_hdr.DataDirectory[2].VirtualAddress), EC32(optional_hdr.DataDirectory[2].Size))) { case 1: cli_dbgmsg("Petite: Unpacked and rebuilt executable saved in %s\n", tempfile); cli_dbgmsg("***** Scanning rebuilt PE file *****\n"); break; case 0: cli_dbgmsg("Petite: Unpacked data saved in %s\n", tempfile); break; default: cli_dbgmsg("Petite: Unpacking failed\n"); } free(dest); fsync(ndesc); lseek(ndesc, 0, SEEK_SET); if(cli_magic_scandesc(ndesc, virname, scanned, engine, limits, options, arec, mrec) == CL_VIRUS) { free(section_hdr); close(ndesc); if(!cli_leavetemps_flag) { unlink(tempfile); free(tempfile); } else { free(tempfile); } return CL_VIRUS; } close(ndesc); if(!cli_leavetemps_flag) { unlink(tempfile); free(tempfile); } else { free(tempfile); } } } /* PESpin 1.1 */ if(nsections > 1 && EC32(optional_hdr.AddressOfEntryPoint) >= EC32(section_hdr[nsections - 1].VirtualAddress) && EC32(optional_hdr.AddressOfEntryPoint) < EC32(section_hdr[nsections - 1].VirtualAddress) + EC32(section_hdr[nsections - 1].SizeOfRawData) - 0x3217 - 4 && memcmp(buff+4, "\xe8\x00\x00\x00\x00\x8b\x1c\x24\x83\xc3", 10) == 0) { struct stat fstats; char *spinned; if(fstat(desc, &fstats) == -1) { free(section_hdr); return CL_EIO; } if((spinned = (char *) cli_malloc(fstats.st_size)) == NULL) { free(section_hdr); return CL_EMEM; } lseek(desc, 0, SEEK_SET); if(read(desc, spinned, fstats.st_size) != fstats.st_size) { cli_dbgmsg("PESpin: Can't read %d bytes\n", fstats.st_size); free(spinned); free(section_hdr); return CL_EIO; } tempfile = cli_gentemp(NULL); if((ndesc = open(tempfile, O_RDWR|O_CREAT|O_TRUNC, S_IRWXU)) < 0) { cli_dbgmsg("PESpin: Can't create file %s\n", tempfile); free(tempfile); free(spinned); free(section_hdr); return CL_EIO; } if(!unspin(spinned, fstats.st_size, section_hdr, nsections - 1, EC32(optional_hdr.AddressOfEntryPoint), ndesc)) { free(spinned); cli_dbgmsg("PESpin: Unpacked and rebuilt executable saved in %s\n", tempfile); fsync(ndesc); lseek(ndesc, 0, SEEK_SET); if(cli_magic_scandesc(ndesc, virname, scanned, engine, limits, options, arec, mrec) == CL_VIRUS) { free(section_hdr); close(ndesc); if(!cli_leavetemps_flag) { unlink(tempfile); free(tempfile); } else { free(tempfile); } return CL_VIRUS; } } else { free(spinned); cli_dbgmsg("PESpin: Rebuilding failed\n"); } close(ndesc); if(!cli_leavetemps_flag) { unlink(tempfile); free(tempfile); } else { free(tempfile); } } /* to be continued ... */ free(section_hdr); return CL_CLEAN; } int cli_peheader(int desc, struct cli_exe_info *peinfo) { uint16_t e_magic; /* DOS signature ("MZ") */ uint32_t e_lfanew; /* address of new exe header */ uint32_t min, max; struct pe_image_file_hdr file_hdr; struct pe_image_optional_hdr optional_hdr; struct pe_image_section_hdr *section_hdr; struct stat sb; int i; unsigned int err; cli_dbgmsg("in cli_peheader\n"); if(read(desc, &e_magic, sizeof(e_magic)) != sizeof(e_magic)) { cli_dbgmsg("Can't read DOS signature\n"); return -1; } if(EC16(e_magic) != IMAGE_DOS_SIGNATURE && EC16(e_magic) != IMAGE_DOS_SIGNATURE_OLD) { cli_dbgmsg("Invalid DOS signature\n"); return -1; } lseek(desc, 58, SEEK_CUR); /* skip to the end of the DOS header */ if(read(desc, &e_lfanew, sizeof(e_lfanew)) != sizeof(e_lfanew)) { cli_dbgmsg("Can't read new header address\n"); /* truncated header? */ return -1; } e_lfanew = EC32(e_lfanew); if(!e_lfanew) { cli_dbgmsg("Not a PE file\n"); return -1; } if(lseek(desc, e_lfanew, SEEK_SET) < 0) { /* probably not a PE file */ cli_dbgmsg("Can't lseek to e_lfanew\n"); return -1; } if(read(desc, &file_hdr, sizeof(struct pe_image_file_hdr)) != sizeof(struct pe_image_file_hdr)) { /* bad information in e_lfanew - probably not a PE file */ cli_dbgmsg("Can't read file header\n"); return -1; } if(EC32(file_hdr.Magic) != IMAGE_NT_SIGNATURE) { cli_dbgmsg("Invalid PE signature (probably NE file)\n"); return -1; } if(EC16(file_hdr.SizeOfOptionalHeader) != sizeof(struct pe_image_optional_hdr)) { cli_warnmsg("Broken PE header detected.\n"); return -1; } peinfo->nsections = EC16(file_hdr.NumberOfSections); if(read(desc, &optional_hdr, sizeof(struct pe_image_optional_hdr)) != sizeof(struct pe_image_optional_hdr)) { cli_dbgmsg("Can't optional file header\n"); return -1; } peinfo->section = (struct cli_exe_section *) cli_calloc(peinfo->nsections, sizeof(struct cli_exe_section)); if(!peinfo->section) { cli_dbgmsg("Can't allocate memory for section headers\n"); return -1; } if(fstat(desc, &sb) == -1) { cli_dbgmsg("fstat failed\n"); free(peinfo->section); return -1; } section_hdr = (struct pe_image_section_hdr *) cli_calloc(peinfo->nsections, sizeof(struct pe_image_section_hdr)); if(!section_hdr) { cli_dbgmsg("Can't allocate memory for section headers\n"); free(peinfo->section); return -1; } for(i = 0; i < peinfo->nsections; i++) { if(read(desc, §ion_hdr[i], sizeof(struct pe_image_section_hdr)) != sizeof(struct pe_image_section_hdr)) { cli_dbgmsg("Can't read section header\n"); cli_dbgmsg("Possibly broken PE file\n"); free(section_hdr); free(peinfo->section); return -1; } peinfo->section[i].rva = EC32(section_hdr[i].VirtualAddress); peinfo->section[i].vsz = EC32(section_hdr[i].VirtualSize); peinfo->section[i].raw = EC32(section_hdr[i].PointerToRawData); peinfo->section[i].rsz = EC32(section_hdr[i].SizeOfRawData); if(!i) { min = EC32(section_hdr[i].VirtualAddress); max = EC32(section_hdr[i].VirtualAddress) + EC32(section_hdr[i].SizeOfRawData); } else { if(EC32(section_hdr[i].VirtualAddress) < min) min = EC32(section_hdr[i].VirtualAddress); if(EC32(section_hdr[i].VirtualAddress) + EC32(section_hdr[i].SizeOfRawData) > max) max = EC32(section_hdr[i].VirtualAddress) + EC32(section_hdr[i].SizeOfRawData); } } if((peinfo->ep = EC32(optional_hdr.AddressOfEntryPoint)) >= min && !(peinfo->ep = cli_rawaddr(EC32(optional_hdr.AddressOfEntryPoint), section_hdr, peinfo->nsections, &err)) && err) { cli_dbgmsg("Possibly broken PE file\n"); free(section_hdr); free(peinfo->section); return -1; } free(section_hdr); return 0; }