/* * Copyright (C) 2006 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., 51 Franklin Street, Fifth Floor, Boston, * MA 02110-1301, USA. */ #if HAVE_CONFIG_H #include "clamav-config.h" #endif #include "others.h" #include "execs.h" #include "pe.h" #include "rebuildpe.h" static int doubledl(char **scur, uint8_t *mydlptr, char *buffer, uint32_t buffersize) { unsigned char mydl = *mydlptr; unsigned char olddl = mydl; mydl*=2; if ( !(olddl & 0x7f)) { if ( *scur < buffer || *scur >= buffer+buffersize-1 ) return -1; olddl = **scur; mydl = olddl*2+1; *scur=*scur + 1; } *mydlptr = mydl; return (olddl>>7)&1; } int cli_unfsg(char *source, char *dest, int ssize, int dsize, char **endsrc, char **enddst) { uint8_t mydl=0x80; uint32_t backbytes, backsize, oldback = 0; char *csrc = source, *cdst = dest; int oob, lostbit = 1; /* I assume buffers size is >0 - No checking! */ *cdst++=*csrc++; while ( 1 ) { if ((oob=doubledl(&csrc, &mydl, source, ssize))) { if (oob == -1) return -1; /* 164 */ backsize = 0; if ((oob=doubledl(&csrc, &mydl, source, ssize))) { if (oob == -1) return -1; /* 16a */ backbytes = 0; if ((oob=doubledl(&csrc, &mydl, source, ssize))) { if (oob == -1) return -1; /* 170 */ lostbit = 1; backsize++; backbytes = 0x10; while ( backbytes < 0x100 ) { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; backbytes = backbytes*2+oob; } backbytes &= 0xff; if ( ! backbytes ) { if (cdst >= dest+dsize) return -1; *cdst++=0x00; continue; } } else { /* 18f */ if (csrc >= source+ssize) return -1; backbytes = *(unsigned char*)csrc; backsize = backsize * 2 + (backbytes & 1); backbytes = (backbytes & 0xff)>>1; csrc++; if (! backbytes) break; backsize+=2; oldback = backbytes; lostbit = 0; } } else { /* 180 */ backsize = 1; do { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; backsize = backsize*2+oob; if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; } while (oob); backsize = backsize - 1 - lostbit; if (! backsize) { /* 18a */ backsize = 1; do { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; backsize = backsize*2+oob; if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; } while (oob); backbytes = oldback; } else { /* 198 */ if (csrc >= source+ssize) return -1; backbytes = *(unsigned char*)csrc; backbytes += (backsize-1)<<8; backsize = 1; csrc++; do { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; backsize = backsize*2+oob; if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; } while (oob); if (backbytes >= 0x7d00) backsize++; if (backbytes >= 0x500) backsize++; if (backbytes <= 0x7f) backsize += 2; oldback = backbytes; } lostbit = 0; } if (!CLI_ISCONTAINED(dest, dsize, cdst, backsize) || !CLI_ISCONTAINED(dest, dsize, cdst-backbytes, backsize)) return -1; while(backsize--) { *cdst=*(cdst-backbytes); cdst++; } } else { /* 15d */ if (cdst < dest || cdst >= dest+dsize || csrc < source || csrc >= source+ssize) return -1; *cdst++=*csrc++; lostbit=1; } } if (endsrc) *endsrc = csrc; if (enddst) *enddst = cdst; return 0; } #ifdef CL_EXPERIMENTAL static int unmew(char *source, char *dest, int ssize, int dsize, char **endsrc, char **enddst) { uint8_t mydl=0x80; uint32_t myeax_backbytes, myecx_backsize, oldback = 0; char *csrc = source, *cdst = dest; int oob, lostbit = 1; *cdst++=*csrc++; while ( 1 ) { if ((oob=doubledl(&csrc, &mydl, source, ssize))) { if (oob == -1) return -1; /* 164 */ myecx_backsize = 0; if ((oob=doubledl(&csrc, &mydl, source, ssize))) { if (oob == -1) return -1; /* 16a */ myeax_backbytes = 0; if ((oob=doubledl(&csrc, &mydl, source, ssize))) { if (oob == -1) return -1; /* 170 */ lostbit = 1; myecx_backsize++; myeax_backbytes = 0x10; while ( myeax_backbytes < 0x100 ) { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; myeax_backbytes = myeax_backbytes*2+oob; } myeax_backbytes &= 0xff; if ( ! myeax_backbytes ) { if (cdst >= dest+dsize) return -1; *cdst++=0x00; /*cli_dbgmsg("X%02x ", *(cdst-1)&0xff);*/ continue; } } else { /* 18f */ if (csrc >= source+ssize) return -1; myeax_backbytes = *(unsigned char*)csrc; myecx_backsize = myecx_backsize * 2 + (myeax_backbytes & 1); myeax_backbytes = (myeax_backbytes & 0xff)>>1; csrc++; if (! myeax_backbytes) { /* cli_dbgmsg("\nBREAK \n"); */ break; } myecx_backsize+=2; oldback = myeax_backbytes; lostbit = 0; } } else { /* 180 */ myecx_backsize = 1; do { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; myecx_backsize = myecx_backsize*2+oob; if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; } while (oob); myecx_backsize = myecx_backsize - 1 - lostbit; if (! myecx_backsize) { /* 18a */ myecx_backsize = 1; do { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; myecx_backsize = myecx_backsize*2+oob; if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; } while (oob); myeax_backbytes = oldback; } else { /* 198 */ if (csrc >= source+ssize) return -1; myeax_backbytes = *(unsigned char*)csrc; myeax_backbytes += (myecx_backsize-1)<<8; myecx_backsize = 1; csrc++; do { if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; myecx_backsize = myecx_backsize*2+oob; if ((oob=doubledl(&csrc, &mydl, source, ssize)) == -1) return -1; } while (oob); if (myeax_backbytes >= 0x7d00) myecx_backsize++; if (myeax_backbytes >= 0x500) myecx_backsize++; if (myeax_backbytes <= 0x7f) myecx_backsize += 2; oldback = myeax_backbytes; } lostbit = 0; } if (!CLI_ISCONTAINED(dest, dsize, cdst, myecx_backsize) || !CLI_ISCONTAINED(dest, dsize, cdst-myeax_backbytes, myecx_backsize)) { cli_dbgmsg("MEW: rete: %d %d %d %d %d || %d %d %d %d %d\n", dest, dsize, cdst, myecx_backsize, CLI_ISCONTAINED(dest, dsize, cdst, myecx_backsize), dest, dsize, cdst-myeax_backbytes, myecx_backsize, CLI_ISCONTAINED(dest, dsize, cdst-myeax_backbytes, myecx_backsize) ); return -1; } while(myecx_backsize--) { *cdst=*(cdst-myeax_backbytes); cdst++; } } else { /* 15d */ if (cdst < dest || cdst >= dest+dsize || csrc < source || csrc >= source+ssize) { cli_dbgmsg("MEW: retf %08x %08x+%08x=%08x, %08x %08x+%08x=%08x\n", cdst, dest, dsize, dest+dsize, csrc, source, ssize, source+ssize); return -1; } *cdst++=*csrc++; /* cli_dbgmsg("Z%02x ", *(cdst-1)&0xff); */ lostbit=1; } } *endsrc = csrc; *enddst = cdst; return 0; } int unmew11(struct pe_image_section_hdr *section_hdr, int sectnum, char *src, int off, int ssize, int dsize, uint32_t base, uint32_t vadd, int uselzma, char **endsrc, char **enddst, int filedesc) { uint32_t entry_point, newedi, loc_ds=dsize, loc_ss=ssize; char *source = src + dsize + off; /*EC32(section_hdr[sectnum].VirtualSize) + off;*/ char *lesi = source + 12, *ledi; char *f1, *f2; int i; struct cli_exe_section *section = NULL; uint32_t vma = base + vadd, size_sum = ssize + dsize; entry_point = cli_readint32(source + 4); /* 2vGiM: ate these safe enough? * yup, if (EC32(section_hdr[i + 1].SizeOfRawData) < ... * ~line #879 in pe.c */ newedi = cli_readint32(source + 8); ledi = src + (newedi - vma); i = 0; ssize -= 12; while (1) { cli_dbgmsg("MEW unpacking section %d (%08x->%08x)\n", i, lesi, ledi); if (!CLI_ISCONTAINED(src, size_sum, lesi, 4) || !CLI_ISCONTAINED(src, size_sum, ledi, 4)) { cli_dbgmsg("Possibly programmer error or hand-crafted PE file, report to clamav team\n"); return -1; } if (unmew(lesi, ledi, loc_ss, loc_ds, &f1, &f2)) { free(section); return -1; } /* we don't need last section in sections since this is information for fixing imptbl */ if (!CLI_ISCONTAINED(src, size_sum, f1, 4)) { free(section); return -1; } /* XXX */ loc_ss -= (f1+4-lesi); loc_ds -= (f2-ledi); ledi = src + (cli_readint32(f1) - vma); lesi = f1+4; if (!uselzma) { uint32_t val = f2 - src; /* round-up to 4k boundary, I'm not sure of this XXX */ val >>= 12; val <<= 12; val += 0x1000; /* eeevil XXX */ section = cli_realloc(section, (i+2)*sizeof(struct cli_exe_section)); section[0].raw = 0; section[0].rva = vadd; section[i+1].raw = val; section[i+1].rva = val + vadd; section[i].rsz = section[i].vsz = i?val - section[i].raw:val; } i++; if (!cli_readint32(f1)) break; } /* LZMA stuff */ if (uselzma) { /* put everything in one section */ i = 1; if (!CLI_ISCONTAINED(src, size_sum, src+uselzma+8, 1)) { cli_dbgmsg("MEW: couldn't access lzma 'special' tag\n"); free(section); return -1; } /* 0x50 -> push eax */ cli_dbgmsg("MEW: lzma %swas used, unpacking\n", (*(src + uselzma+8) == '\x50')?"special ":""); if (!CLI_ISCONTAINED(src, size_sum, f1+4, 20 + 4 + 5)) { cli_dbgmsg("MEW: lzma initialization data not available!\n"); free(section); return -1; } if(mew_lzma(&(section_hdr[sectnum]), src, f1+4, size_sum, vma, *(src + uselzma+8) == '\x50')) { free(section); return -1; } loc_ds >>= 12; loc_ds <<= 12; loc_ds += 0x1000; /* I have EP but no section's information, so I weren't sure what to do with that */ /* 2vGiM: sounds fair */ section = cli_calloc(1, sizeof(struct cli_exe_section)); section[0].raw = 0; section[0].rva = vadd; section[0].rsz = section[0].vsz = dsize; } if ((f1 = cli_rebuildpe(src, section, i, base, entry_point - base, 0, 0, filedesc))) { if (cli_writen(filedesc, f1, 0x148+0x80+0x28*i+dsize) == -1) { free(f1); return -1; } } else { cli_dbgmsg("MEW: Rebuilding failed\n"); return -1; } return 1; } #endif