Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition on a targeted system. Updates are available.
Description
Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
The vulnerability is due to errors processing Border Gateway Protocol (BGP) route updates that contain malformed attributes. An unauthenticated, remote attacker could exploit this vulnerability by sending malicious BGP route updates to a targeted device. When processed, the route updates could cause the device to distribute corrupted routes to neighboring devices. Devices that accept the corrupted routes could close BGP sessions, resulting in a DoS condition.
Cisco confirmed this vulnerability and software updates are available.
Warning Indicators
The following Cisco IOS Software Releases are vulnerable:
Cisco IOS Software Releases 15.2S, 15.2(1)S, and 15.2(1)S1
To exploit this vulnerability, at least one BGP session must be established between a neighboring device and a targeted device for an attacker to send malicious route updates. In addition, an attacker would likely need access to internal, trusted networks in which these devices reside.
Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.
An unauthenticated, remote attacker could exploit this vulnerability to cause a targeted device to reset all BGP peer sessions. Repeated exploitation may result in an inability to route packets to BGP neighbors during reconvergence times, resulting in a DoS condition.
Technical Information
The vulnerability is due to errors in processing BGP route updates that contain malformed attributes from a peer on an existing BGP session. When processing the update, the affected software may corrupt the attribute before passing the route update to other peers, which may cause BGP neighbors to reset an established BGP session.
An unauthenticated, remote attacker could exploit this vulnerability by sending a malicious route update to the targeted device. When processed, the route update may reset all BGP peers, which would prevent packets from routing to neighboring devices, resulting in a DoS condition.
Safeguards
Administrators are advised to apply the appropriate updates.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit this vulnerability.
A reference document for helping administrators protect BGP is available at the following link: Protecting BGP
Administrators are advised to monitor affected systems.
Patches/Software
Cisco customers with active contracts can obtain updates through the Software Center at the following link: Cisco. Cisco customers without contracts can obtain upgrades by contacting the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via e-mail at tac@cisco.com.
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
The security vulnerability applies to the following combinations of products.
Primary Products:
Cisco
Cisco IOS XR Software
4.1 .0, .1, .2 | 4.2 .0, .1, .2
Cisco
IOS
15.2S 15.2(1)S, 15.2(1)S1
Associated Products:
N/A
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