/*
* Copyright (C) 2004 Tomasz Kojm <tkojm@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 "scanners.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 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)
{
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);
return -1;
}
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_memstr(const char *haystack, int hs, const char *needle, int ns)
{
const char *pt;
int n;
if(!memcmp(haystack, needle, ns))
return 1;
pt = haystack;
n = hs;
while(n && (pt = memchr(pt, needle[0], n))) {
n--;
if(!memcmp(pt, needle, ns))
return 1;
}
return 0;
}
int cli_scanpe(int desc, const char **virname, long int *scanned, const struct cl_node *root, const struct cl_limits *limits, int options, int *arec, 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[256], *tempfile;
int i, found, upx_success = 0, broken = 0, min = 0, max = 0;
int (*upxfn)(char *, int , char *, int) = NULL;
char *src, *dest;
int ssize, dsize, ndesc;
if(read(desc, &e_magic, sizeof(e_magic)) != sizeof(e_magic)) {
cli_dbgmsg("Can't read DOS signature\n");
return CL_EIO;
}
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");
return CL_EIO;
}
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;
}
/* cli_dbgmsg("Machine type: "); */
switch(EC16(file_hdr.Machine)) {
case 0x14c:
cli_dbgmsg("Machine type: 80386\n");
break;
case 0x014d:
cli_dbgmsg("Machine type: 80486\n");
break;
case 0x014e:
cli_dbgmsg("Machine type: 80586\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 0x1f0:
cli_dbgmsg("Machine type: PowerPC\n");
break;
default:
cli_warnmsg("Unknown machine type in PE header\n");
}
nsections = EC16(file_hdr.NumberOfSections);
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");
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");
return CL_EIO;
}
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 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;
default:
cli_warnmsg("Unknown subsystem in PE header\n");
}
cli_dbgmsg("NumberOfRvaAndSizes: %d\n", EC32(optional_hdr.NumberOfRvaAndSizes));
cli_dbgmsg("------------------------------------\n");
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);
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");
cli_dbgmsg("------------------------------------\n");
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(fstat(desc, &sb) == -1) {
cli_dbgmsg("fstat failed\n");
free(section_hdr);
return CL_EIO;
}
if((ep = cli_rawaddr(EC32(optional_hdr.AddressOfEntryPoint), section_hdr, nsections)) == -1) {
cli_dbgmsg("Possibly broken PE file\n");
broken = 1;
}
/* simple sanity check */
if(!broken && EC32(section_hdr[nsections - 1].PointerToRawData) + EC32(section_hdr[nsections - 1].SizeOfRawData) > sb.st_size) {
cli_dbgmsg("Possibly broken PE file - Section %d out of file (Offset@ %d, Rsize %d, Total filesize %d, EP@ %d)\n", nsections - 1, EC32(section_hdr[nsections - 1].PointerToRawData), EC32(section_hdr[nsections - 1].SizeOfRawData), sb.st_size, ep);
broken = 1;
}
if(broken) {
free(section_hdr);
return CL_CLEAN;
}
cli_dbgmsg("EntryPoint offset: 0x%x (%d)\n", ep, ep);
/* UPX support */
/* try to find the first section with physical size == 0 */
found = 0;
for(i = 0; i < 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: empty section found - assuming UPX compression\n");
break;
}
}
if(found) {
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);
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, sizeof(char))) == NULL) {
free(section_hdr);
free(src);
return CL_EMEM;
}
lseek(desc, EC32(section_hdr[i + 1].PointerToRawData), SEEK_SET);
if(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);
free(section_hdr);
free(src);
free(dest);
return CL_EIO;
} 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))
upx_success = 1;
} else {
cli_dbgmsg("UPX: UPX1 seems skewed by %d bytes\n", skew);
if(!upxfn(src + skew, ssize - skew, dest, dsize) || !upxfn(src, ssize, dest, dsize))
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) && upx_inflate2b(src + 0x15, ssize - 0x15, dest, dsize) ) {
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) && upx_inflate2d(src+0x15, ssize-0x15, dest, dsize) ) {
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) && upx_inflate2e(src + 0x15, ssize - 0x15, dest, dsize) ) {
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");
} else {
int ndesc;
if(cli_leavetemps_flag) {
tempfile = cli_gentemp(NULL);
if((ndesc = open(tempfile, O_WRONLY|O_CREAT|O_TRUNC, S_IRWXU)) < 0) {
cli_dbgmsg("UPX: Can't create file %s\n", tempfile);
free(tempfile);
free(section_hdr);
free(src);
free(dest);
return CL_EIO;
}
if(write(ndesc, dest, dsize) != dsize) {
cli_dbgmsg("Can't write %d bytes\n", dsize);
free(tempfile);
free(section_hdr);
free(src);
free(dest);
return CL_EIO;
}
close(ndesc);
cli_dbgmsg("UPX: Decompressed data saved in %s\n", tempfile);
free(tempfile);
}
if(cl_scanbuff(dest, dsize, virname, root) == CL_VIRUS) {
free(section_hdr);
free(src);
free(dest);
return CL_VIRUS;
}
}
free(src);
free(dest);
}
/* Petite */
/*
found = 2;
lseek(desc, ep, SEEK_SET);
if(read(desc, buff, 200) != 200)
return CL_EIO;
if(buff[0] != '\xb8' || cli_readint32(buff + 1) != EC32(section_hdr[nsections - 1].VirtualAddress) + EC32(optional_hdr.ImageBase)) {
if(buff[0] != '\xb8' || 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);
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++) {
lseek(desc, cli_rawaddr(EC32(section_hdr[i].VirtualAddress), section_hdr, nsections), SEEK_SET);
read(desc, dest + EC32(section_hdr[i].VirtualAddress) - min, EC32(section_hdr[i].SizeOfRawData));
}
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;
}
switch(petite_inflate2x_1to9(dest, min, max - min, section_hdr,
nsections, EC32(optional_hdr.ImageBase), ep, 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);
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, root, 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);
}
}
}
*/
/* to be continued ... */
free(section_hdr);
return CL_CLEAN;
}