CVE-2007-5583 in IP Phone
Summary
by MITRE
Cisco IP Phone 7940 with firmware P0S3-08-7-00 allows remote attackers to cause a denial of service ("486 Busy" responses or device reboot) via a sequence of SIP INVITE transactions in which the Request-URI lacks a user name, a different vulnerability than CVE-2007-4459.
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Analysis
by VulDB Data Team • 10/12/2024
The vulnerability identified as CVE-2007-5583 affects Cisco IP Phone 7940 devices running firmware version P0S3-08-7-00 and represents a significant denial of service weakness within the Session Initiation Protocol implementation. This flaw specifically manifests when the device receives SIP INVITE transactions where the Request-URI is missing a user name component, creating a condition that can be exploited by remote attackers to disrupt normal phone operations. The vulnerability operates through a sequence of carefully crafted SIP messages that exploit the device's insufficient input validation mechanisms, leading to either the generation of "486 Busy" responses or complete device reboot cycles that effectively deny service to legitimate users.
The technical implementation of this vulnerability stems from the device's failure to properly validate SIP Request-URI formats during INVITE processing. When a SIP INVITE message arrives with a Request-URI that lacks the required user name portion, the Cisco IP Phone 7940 does not adequately handle this malformed input. This processing failure creates a condition where the device's SIP stack becomes unstable, resulting in either the device responding with a 486 Busy error code to indicate that the call cannot be completed due to the malformed request, or in more severe cases, causing the device to completely reboot. The vulnerability specifically differs from CVE-2007-4459 in its attack vector and the particular sequence of SIP transactions required to trigger the condition, making it a distinct but related weakness in the device's SIP processing capabilities.
The operational impact of CVE-2007-5583 extends beyond simple service disruption to potentially compromise business continuity and communication reliability within enterprise environments. When exploited, the vulnerability can cause significant downtime for users who rely on the affected IP phones for critical communications, particularly in mission-critical environments where phone availability is essential. The "486 Busy" responses can make it appear that the phone is simply busy or unavailable, leading to confusion among users and potentially causing missed communications. The device reboot condition is more severe as it can result in complete loss of phone functionality until manual intervention or automatic recovery occurs, which may not be immediate. Organizations with multiple affected devices could experience cascading failures that impact overall communication infrastructure and require significant troubleshooting efforts.
This vulnerability aligns with CWE-20, which addresses "Improper Input Validation," and demonstrates the critical importance of proper validation of network protocol inputs in telephony systems. The attack pattern follows techniques described in the ATT&CK framework under T1499.004 for Network Denial of Service, where attackers exploit weaknesses in network infrastructure to disrupt services. The vulnerability also reflects broader concerns about secure implementation of SIP protocol handling in VoIP devices, as identified in various cybersecurity frameworks that emphasize the need for robust input validation and error handling in communication protocols. Organizations should implement network segmentation to limit exposure, deploy intrusion detection systems to monitor for suspicious SIP traffic patterns, and ensure timely firmware updates are applied to address known vulnerabilities in their telephony infrastructure.