CVE-2022-20694 in IOS XE
Summary
by MITRE • 04/15/2022
A vulnerability in the implementation of the Resource Public Key Infrastructure (RPKI) feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the Border Gateway Protocol (BGP) process to crash, resulting in a denial of service (DoS) condition. This vulnerability is due to the incorrect handling of a specific RPKI to Router (RTR) Protocol packet header. An attacker could exploit this vulnerability by compromising the RPKI validator server and sending a specifically crafted RTR packet to an affected device. Alternatively, the attacker could use man-in-the-middle techniques to impersonate the RPKI validator server and send a crafted RTR response packet over the established RTR TCP connection to the affected device. A successful exploit could allow the attacker to cause a DoS condition because the BGP process could constantly restart and BGP routing could become unstable.
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Analysis
by VulDB Data Team • 04/20/2022
The vulnerability described in CVE-2022-20694 represents a critical flaw in Cisco IOS XE Software's implementation of the Resource Public Key Infrastructure feature, specifically affecting the RPKI to Router protocol communication. This issue manifests as a denial of service condition that directly impacts Border Gateway Protocol operations within network infrastructure. The vulnerability stems from improper handling of RTR protocol packet headers, which are essential for validating Internet routing information through the RPKI framework. The RPKI system serves as a critical security mechanism that helps prevent route hijacking and ensures the authenticity of routing information exchanged between network devices. When properly implemented, RPKI validates the legitimacy of BGP announcements by verifying that routing prefixes are authorized by their respective network owners, making it a cornerstone of modern Internet security practices.
The technical exploitation of this vulnerability requires an attacker to manipulate the RTR protocol communication between a router and an RPKI validator server. The flaw occurs when an attacker can either compromise the RPKI validator server itself or employ man-in-the-middle techniques to impersonate the legitimate server within an established RTR TCP connection. This attack vector specifically targets the packet header processing logic within the IOS XE software implementation, where malformed or specially crafted RTR packets can trigger unexpected behavior in the BGP process. The vulnerability does not require authentication credentials from the attacker, making it particularly dangerous as it can be exploited remotely without prior access to the network. The improper header handling causes the BGP process to crash repeatedly, leading to continuous restart cycles that destabilize routing operations and create service disruption across the affected network infrastructure.
The operational impact of this vulnerability extends beyond simple service interruption to potentially compromise the entire routing stability of networks relying on RPKI validation. When the BGP process becomes unstable due to constant restarts, it can cause routing flapping, where network paths frequently change and become unavailable. This instability affects the reliability of Internet connectivity for organizations using the affected Cisco devices, potentially leading to significant service degradation or complete routing failures. The vulnerability affects network security posture by weakening the integrity of routing information validation, which could make networks more susceptible to route hijacking attacks or other BGP-related security incidents. Organizations implementing RPKI validation as part of their network security strategy would experience a direct degradation of their security controls, as the mechanism designed to protect against routing attacks becomes a potential attack vector itself.
Mitigation strategies for CVE-2022-20694 should focus on both immediate defensive measures and long-term architectural improvements. Network administrators should implement access controls to restrict RTR protocol communication to trusted RPKI validator servers, using network segmentation and firewall rules to limit exposure. The Cisco IOS XE software should be updated to versions that contain the patched RTR packet header validation logic, which addresses the root cause of the vulnerability. Organizations should also consider implementing monitoring solutions that can detect abnormal BGP process restart patterns or unusual RTR protocol activity that might indicate exploitation attempts. The vulnerability aligns with CWE-129, which covers improper validation of array index, and relates to ATT&CK technique T1566.002 for social engineering via phishing. Network defenders should also consider disabling RPKI validation temporarily if immediate patching is not possible, though this reduces overall security. The incident highlights the importance of secure implementation of critical network protocols and the need for thorough testing of security features before deployment in production environments.