CVE-2009-5040 in IOS
Summary
by MITRE
CallManager Express (CME) on Cisco IOS before 15.0(1)XA allows remote authenticated users to cause a denial of service (device crash) by using an extension mobility (EM) phone to interact with the menu for SNR number changes, aka Bug ID CSCta63555.
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Analysis
by VulDB Data Team • 10/11/2021
Cisco CallManager Express running IOS versions prior to 15.0(1)XA contains a vulnerability in the extension mobility phone menu processing functionality that enables authenticated remote attackers to trigger a device crash through malformed SNR number change menu interactions. This vulnerability specifically affects the handling of extension mobility phone objects when they attempt to access or modify the SNR number change menu interface, leading to a denial of service condition that results in the complete device crash and subsequent service interruption.
The technical flaw stems from insufficient input validation and error handling within the extension mobility subsystem of CME. When an authenticated extension mobility phone attempts to interact with the SNR number change menu, the system fails to properly validate the input parameters or handle malformed menu requests, causing a buffer overflow or memory corruption condition that ultimately leads to the device crashing and requiring manual restart to restore service. This vulnerability operates at the application layer and leverages the existing authentication mechanisms to gain access to privileged menu functions, making it particularly dangerous as it requires minimal privileges beyond basic authentication.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the availability of the entire CallManager Express service. Network administrators face the challenge of maintaining voice communication services when malicious actors can remotely crash the device, potentially leading to extended downtime and business disruption. The vulnerability affects organizations relying on CME for small to medium business voice solutions, where the device crash can impact all phone extensions managed by that particular CME instance, causing cascading failures in communication infrastructure.
Mitigation strategies should focus on immediate patching to IOS version 15.0(1)XA or later, which contains the necessary code fixes addressing the input validation issues in the extension mobility menu processing. Organizations should also implement network segmentation to limit access to CME devices and restrict extension mobility phone access to authorized personnel only. Monitoring and logging should be enhanced to detect unusual menu interaction patterns that may indicate exploitation attempts. From a cybersecurity perspective, this vulnerability aligns with CWE-121 for buffer overflow conditions and maps to ATT&CK technique T1499.004 for network denial of service attacks. The vulnerability demonstrates the importance of proper input validation and error handling in telephony systems, particularly in enterprise voice infrastructure where availability is critical for business operations and compliance requirements mandate continuous service availability.