bool find_section(PE_FILE *pe, IMAGE_SECTION_HEADER *sec, bool executable)
{
rewind(pe->handle);
if (!pe_get_sections(pe))
return false;
if (fseek(pe->handle, pe->addr_sections, SEEK_SET))
return false;
for (unsigned int i=0; i < pe->num_sections; i++)
{
fread(sec, sizeof(*sec), 1, pe->handle);
if (executable && (sec->Characteristics & 0x20))
return true;
}
return false;
}
static void print_strange_sections(PE_FILE *pe)
{
bool aux = false;
if (!pe_get_sections(pe) || !pe->num_sections)
return;
if (pe->num_sections <= 2)
snprintf(value, MAX_MSG, "%d (low)", pe->num_sections);
else if (pe->num_sections > 8)
snprintf(value, MAX_MSG, "%d (high)", pe->num_sections);
else
snprintf(value, MAX_MSG, "%d", pe->num_sections);
output("section count", value);
for (unsigned i=0; i < pe->num_sections && i <= 65535; i++, aux=false)
{
memset(&value, 0, sizeof(value));
if (!strisprint((const char *)pe->sections_ptr[i]->Name))
stradd(value, "suspicious name", &aux);
if (!pe->sections_ptr[i]->SizeOfRawData)
stradd(value, "zero length", &aux);
else if (pe->sections_ptr[i]->SizeOfRawData <= 512)
stradd(value, "small length", &aux);
// rwx or writable + executable code
if (pe->sections_ptr[i]->Characteristics & 0x80000000 &&
(pe->sections_ptr[i]->Characteristics & 0x20 ||
pe->sections_ptr[i]->Characteristics & 0x20000000))
stradd(value, "self-modifying", &aux);
if (!aux)
strncpy(value, "normal", 7);
output((char *)pe->sections_ptr[i]->Name, value);
}
}
static IMAGE_SECTION_HEADER *pe_check_fake_entrypoint(PE_FILE *pe, DWORD *ep)
{
IMAGE_SECTION_HEADER *epsec = NULL;
if (!pe->optional_ptr)
pe_get_optional(pe);
if (!pe->num_sections || !pe->sections_ptr)
pe_get_sections(pe);
if (!pe->num_sections)
return NULL;
epsec = pe_rva2section(pe, *ep);
if (!epsec)
return NULL;
if (!(epsec->Characteristics & 0x20))
return epsec;
return NULL;
}
/*
* -1 - fake tls callbacks detected
* 0 - no tls directory
* >0 - number of callbacks functions found
*/
static int pe_get_tls_callbacks(PE_FILE *pe)
{
QWORD tls_addr = 0;
int ret = 0;
if (!pe)
return 0;
tls_addr = pe_get_tls_directory(pe);
if (!tls_addr || !pe_get_sections(pe))
return 0;
// search for tls in all sections
for (unsigned int i=0, j=0; i < pe->num_sections; i++)
{
if (tls_addr >= pe->sections_ptr[i]->VirtualAddress &&
tls_addr < (pe->sections_ptr[i]->VirtualAddress + pe->sections_ptr[i]->SizeOfRawData))
{
unsigned int funcaddr = 0;
if (fseek(pe->handle, tls_addr - pe->sections_ptr[i]->VirtualAddress
+ pe->sections_ptr[i]->PointerToRawData, SEEK_SET))
return 0;
if (pe->architecture == PE32)
{
IMAGE_TLS_DIRECTORY32 tlsdir32;
if (!fread(&tlsdir32, sizeof(tlsdir32), 1, pe->handle))
return 0;
if (! (tlsdir32.AddressOfCallBacks & pe->optional_ptr->_32->ImageBase))
break;
if (fseek(pe->handle,
rva2ofs(pe, tlsdir32.AddressOfCallBacks - pe->optional_ptr->_32->ImageBase), SEEK_SET))
return 0;
}
else if (pe->architecture == PE64)
{
IMAGE_TLS_DIRECTORY64 tlsdir64;
if (!fread(&tlsdir64, sizeof(tlsdir64), 1, pe->handle))
return 0;
if (! (tlsdir64.AddressOfCallBacks & pe->optional_ptr->_64->ImageBase))
break;
if (fseek(pe->handle,
rva2ofs(pe, tlsdir64.AddressOfCallBacks - pe->optional_ptr->_64->ImageBase), SEEK_SET))
return 0;
}
else
return 0;
ret = -1; // tls directory and section exists
do
{
fread(&funcaddr, sizeof(int), 1, pe->handle);
if (funcaddr)
{
char value[MAX_MSG];
ret = ++j; // function found
if (config.verbose)
{
snprintf(value, MAX_MSG, "%#x", funcaddr);
output("TLS callback function", value);
}
}
} while (funcaddr);
return ret;
}
}
return 0;
}
int main(int argc, char *argv[])
{
PE_FILE pe;
FILE *fp = NULL;
if (argc < 2)
{
usage();
exit(1);
}
parse_options(argc, argv); // opcoes
if ((fp = fopen(argv[argc-1], "rb")) == NULL)
EXIT_ERROR("file not found or unreadable");
pe_init(&pe, fp); // inicializa o struct pe
if (!is_pe(&pe))
EXIT_ERROR("not a valid PE file");
// dos header
if (config.dos || config.all_headers || config.all)
{
IMAGE_DOS_HEADER dos;
if (pe_get_dos(&pe, &dos))
print_dos_header(&dos);
else { EXIT_ERROR("unable to read DOS header"); }
}
// coff/file header
if (config.coff || config.all_headers || config.all)
{
IMAGE_COFF_HEADER coff;
if (pe_get_coff(&pe, &coff))
print_coff_header(&coff);
else { EXIT_ERROR("unable to read COFF file header"); }
}
// optional header
if (config.opt || config.all_headers || config.all)
{
if (pe_get_optional(&pe))
print_optional_header(&pe);
else { EXIT_ERROR("unable to read Optional (Image) file header"); }
}
// directories
if (config.dirs || config.all)
{
if (pe_get_directories(&pe))
print_directories(&pe);
else { EXIT_ERROR("unable to read the Directories entry from Optional header"); }
}
// imports
if (config.imports || config.all)
{
if (pe_get_directories(&pe))
print_imports(&pe);
else { EXIT_ERROR("unable to read the Directories entry from Optional header"); }
}
// exports
if (config.exports || config.all)
{
if (pe_get_directories(&pe))
print_exports(&pe);
else
{ EXIT_ERROR("unable to read directories from optional header"); }
}
// sections
if (config.all_sections || config.all)
{
if (pe_get_sections(&pe))
print_sections(&pe);
else { EXIT_ERROR("unable to read sections"); }
}
// free
pe_deinit(&pe);
return 0;
}