Snort TTL security bypass
| snort-ttl-security-bypass (42584) |  Low 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
- SA30348: Snort Fragmented IP Packets TTL Security Bypass
- SECTRACK ID: 1020081: Snort Bug in Processing Fragmented Packets Lets Remote Users Evade Detection
- VUPEN/ADV-2008-1602: Snort Fragmented IP Packets Handling Filter Evasion Vulnerability
Platforms Affected:
- MandrakeSoft Mandrake Linux 2008.0
- MandrakeSoft Mandrake Linux 2008.0 X86_64
- MandrakeSoft Mandrake Linux 2008.1
- MandrakeSoft Mandrake Linux 2008.1 X86_64
- Snort Snort 2.6
- Snort Snort 2.8
Reported:
May 21, 2008
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For corrections or additions please email xforce@iss.net
* According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.
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.