Vigil@nce: Cisco IOS, denial of service via BGP
August 2009 by Vigil@nce
A malicious peer can send BGP packets in order to force the router to restart.
Consequences: denial of service of computer
Provenance: intranet client
Means of attack: no proof of concept, no attack
Ability of attacker: expert (4/4)
Confidence: confirmed by the editor (5/5)
Diffusion of the vulnerable configuration: high (3/3)
Number of vulnerabilities in this bulletin: 2
Creation date: 29/07/2009
DESCRIPTION OF THE VULNERABILITY
The RFC 4893 extents the BGP protocol to support ASN (Autonomous System Number) on 4 bytes, instead of 2 bytes. When an IOS router supports ASN-4, a malicious peer can generate two vulnerabilities.
An attacker can send more than one thousand BGP Updates using ASN-2, to generate a denial of service. [grav:2/4; BID-35860, CSCsy86021]
An attacker can send a malformed BGP Update using ASN-2, to generate a denial of service. [grav:2/4; BID-35862, CSCta33973, CVE-2009-2049]
A malicious peer can therefore send BGP packets in order to force the router to restart.
Identifiers: 110457, BID-35860, BID-35862, cisco-sa-20090729-bgp, CSCsy86021, CSCta33973, CVE-2009-2049, VIGILANCE-VUL-8901