Snort TTL security bypass

snort-ttl-security-bypass (42584) The risk level is classified as LowLow Risk

Description:

Snort could allow a remote attacker to bypass security restrictions, caused by an error during packet reassembly. When the Time To Live (TTL) value of a packet fragment exceeds the configured threshold, the packet will be dropped. By fragmenting packets for the intended destination, an attacker could exploit this vulnerability to bypass Snort rules.

*CVSS:

Base Score: 5
  Access Vector: Network
  Access Complexity: Low
  Authentication: None
  Confidentiality Impact: None
  Integrity Impact: Partial
  Availability Impact: None
 
Temporal Score: 3.7
  Exploitability: Unproven
  Remediation Level: Official-Fix
  Report Confidence: Confirmed

Consequences:

Bypass Security

Remedy:

Upgrade to the latest version of Snort (2.8.1 or later), available from the Snort Web site. See References.

References:

  • iDefense Labs PUBLIC ADVISORY: 05.21.08: Multiple Vendor Snort IP Fragment TTL Evasion Vulnerability.
  • Snort Web site: Snort Downloads.
  • BID-29327: Snort Time To Live Fragment Reassembly Security Bypass Weakness
  • CVE-2008-1804: preprocessors/spp_frag3.c in Sourcefire Snort before 2.8.1 does not properly identify packet fragments that have dissimilar TTL values, which allows remote attackers to bypass detection rules by using a different TTL for each fragment.
  • MDVSA-2009:259: snort
  • MDVSA-2009:259-1: snort
  • OSVDB ID: 45452: Snort Fragmented IP Packets TTL Traffic Filtering Bypass
  • SA30348: Snort Fragmented IP Packets TTL Security Bypass
  • SECTRACK ID: 1020081: Snort Bug in Processing Fragmented Packets Lets Remote Users Evade Detection

Platforms Affected:

  • MandrakeSoft Mandrake Linux 2008.0 X86_64
  • MandrakeSoft Mandrake Linux 2008.0
  • MandrakeSoft Mandrake Linux 2008.1 X86_64
  • MandrakeSoft Mandrake Linux 2008.1
  • Snort Snort 2.6
  • Snort Snort 2.8

Reported:

May 21, 2008

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The information within this database may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall IBM be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information.

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