Cisco IOS GRE decapsulation ACL bypass
| cisco-ios-gre-acl-bypass (28786) |  Medium Risk |
Description:
Cisco IOS could allow a remote attacker to bypass Access Control Lists (ACLs), caused by improper parsing of Generic Routing Encapsulation (GRE) packets. An attacker could exploit this vulnerability by sending a specially-crafted GRE packet containing invalid source routing information.
*CVSS:
| Base Score: | 3.5 |
| Access Vector: | Remote |
| Access Complexity: | Low |
| Authentication: | Not Required |
| Confidentiality Impact: | None |
| Integrity Impact: | Partial |
| Availability Impact: | None |
| Temporal Score: | 2.6 |
| Exploitability: | Unproven |
| Remediation Level: | Official-Fix |
| Report Confidence: | Confirmed |
Consequences:
Bypass Security
Remedy:
Refer to cisco-sr-20060906-gre for patch, upgrade or suggested workaround information. See References.
References:
- BugTraq Mailing List, Wed Sep 06 2006 - 11:33:44 CDT : Cisco IOS GRE issue.
- cisco-sr-20060906-gre: Cisco Security Response to: Cisco IOS GRE Decapsulation Vulnerability.
- BID-19878: Cisco IOS Multiple GRE Source Routing Vulnerabilities
- CVE-2006-4650: Cisco IOS 12.0, 12.1, and 12.2, when GRE IP tunneling is used and the RFC2784 compliance fixes are missing, does not verify the offset field of a GRE packet during decapsulation, which leads to an integer overflow that references data from incorrect memory locations, which allows remote attackers to inject crafted packets into the routing queue, possibly bypassing intended router ACLs.
- OSVDB ID: 28590: Cisco IOS GRE Packet Decapsulation
- SA21783: Cisco IOS GRE Decapsulation Vulnerability
- SECTRACK ID: 1016799: Cisco IOS GRE Parsing Error May Let Remote Users Inject Packets
- VUPEN/ADV-2006-3502: Cisco IOS GRE Decapsulation Access Control Lists Security Bypass Vulnerability
Platforms Affected:
- Cisco IOS 12.0
- Cisco IOS 12.1
- Cisco IOS 12.2
Reported:
Sep 06, 2006
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* 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.