Vulnerability Note VU#327976
Cisco Adaptive Security Appliance (ASA) IKEv1 and IKEv2 contains a buffer overflow vulnerability
Original Release date: 11 Feb 2016 | Last revised: 11 Feb 2016

Cisco Adaptive Security Appliance (ASA) Internet Key Exchange versions 1 and 2 (IKEv1 and IKEv2) contains a buffer overflow vulnerability that may be leveraged to gain remote code execution.

CWE-119: Improper Restriction of Operations within the Bound of a Memory Buffer – CVE-2016-1287
According to the advisory by Exodus Intelligence:

The algorithm for re-assembling IKE payloads fragmented with the Cisco fragmentation protocol contains a bounds-checking flaw that allows a heap buffer to be overflowed with attacker-controlled data. A sequence of payloads with carefully chosen parameters causes a buffer of insufficient size to be allocated in the heap which is then overflowed when fragment payloads are copied into the buffer. Attackers can use this vulnerability to execute arbitrary code on affected devices.

Systems that are configured to terminate IKEv1 and IKEv2 VPN connections are vulnerable to exploitation. The Cisco security advisory describes how to determine if a system is configured in a vulnerable manner by checking the running crypto maps.

By sending specially crafted UDP packets directly to affected devices, a remote, unauthenticated attacker may be able to execute arbitrary code and gain full control of affected systems.

Apply an update

Cisco has issued updates for several versions of ASA to address this vulnerability. Users are encouraged to update to the latest version.

Note that Cisco ASA versions 7.2, 8.2, 8.3, and 8.6 are affected but no longer supported by the vendor. Users of these versions should strongly consider migrating to a supported solution.
Detect and filter malicious packets

According to the advisory by Exodus Intelligence:

Looking for the value of the length field of a Fragment Payload (type 132) IKEv2 or IKEv1 packet allows detecting an exploitation attempt. Any length field with a value < 8 must be considered as an attempt to exploit the vulnerability. The detection also has to deal with the fact that the multiple payloads can be chained inside an IKEv2 packet, and that the Fragment Payload may not be the only/first payload of the packet.

Network administrators may consider implementing rules to detect or block attacks.

Vendor Information (Learn More)

VendorStatusDate NotifiedDate UpdatedCiscoAffected-11 Feb 2016If you are a vendor and your product is affected, let
us know.

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Cisco credits David Barksdale, Jordan Gruskovnjak, and Alex Wheeler of Exodus Intelligence for reporting this vulnerability.
This document was written by Joel Land.

Other Information


Date Public:
11 Feb 2016

Date First Published:
11 Feb 2016

Date Last Updated:
11 Feb 2016

Document Revision:

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