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Age in Days
CVSS Score
Patch within next
Risk Level

992


10.0

Immediately

Critical

 

This vulnerability is 2 years 8 months and 19 days old there are exploits publicly available for it. The vulnerability itself is over a year old, and with there being exploits publicly available it is highly advisable that this vulnerability is patched immediately.

 

Synopsis

The remote device is missing a vendor-supplied security patch.

 

Vulnerability Description

The vulnerability affects the (Internet Key Exchange) IKE protocols within the IPsec protocol suite that are used to establish VPN connections.

Cisco provides a feature on their ASA appliances providing the fragmentation of large IKE packets. When large IKE packet fragments are received, they are assembled by the Cisco fragmentation protocol however the code implementing this protocol contains a bounds-checking flaw similar to the HeartBleed vulnerability from 2014. This flaw allows an attacker to cause a buffer overflow, specifically a heap overflow, with attacker provided data.

The vulnerability itself is caused by sending a sequence of specifically crafted packets, causing the heap that is expecting fragmented packets to be set too small. The insufficiently sized memory buffer is then overflowed when the attacker’s payload is copied into the buffer, causing an access violation during reassembly of the fragmented IKE packets.

Attackers can leverage this access violation to perform a Denial of Service (DoS) attack against the ASA appliance. However, several contributing flaws may allow attackers to perform Remote Code Execution (RCE), which may see working exploits in the wild in the near future due to the high profile nature of this vulnerability.

To execute any attack against an ASA device an attacker must leverage a re-initialization flaw, 2 logic flaws and an input validation flaw to control the memory execution flow to run arbitrary code on the appliance.

This vulnerability is a combination of the following vulnerabilities in the Internet Key Exchange (IKE) implementation:

  • An overflow condition exists in both the IKE and IKEv2 implementations due to improper validation of user-supplied input when handling UDP packets. An unauthenticated, remote attacker can exploit this issue, via specially crafted UDP packets, to cause a buffer overflow condition, resulting in a denial of service or the execution of arbitrary code. (CVE-2016-1287)
  • A denial of service vulnerability exists in the IKEv2 implementation due to improper handling of fragmented IKEv2 packets. An unauthenticated, remote attacker can exploit this issue, via specially crafted UDP packets, to cause the device to reload. (CVE-2016-1344)
Further information about the vulnerability has been published by Cisco in three bug releases:

 

Solution

Upgrade to the relevant fixed version referenced in Cisco Security Advisories cisco-sa-20160210-asa-ike and cisco-sa-20160323-ios-ikev2.

 

Further Information


 

CVE References

CVE-2016-1287 NIST | MITRE | CVEDetails
CVE-2016-1344 NIST | MITRE | CVEDetails

 

Get in touch

Should you have any questions regarding this or any security matter, please do not hesitate to get in touch by emailing the Hedgehog Cyber Operations Team.

Whilst every effort is made to ensure the accuracy and robustness of any information presented, it is not possible for Hedgehog Cyber to test every possible scenario an organisation may face, and Hedgehog Cyber cannot be held liable for any loss or damage which may arise from taking action on any of the contents provided. Hedgehog Cyber strongly advises that all recommendations, solutions and detection methods detailed, are thoroughly reviewed and tested in non-production environments before being considered suitable for production release, in-line with any existing internal change control procedures.