CVE-2007-1561 in IP Phone
Summary
by MITRE
The channel driver in Asterisk before 1.2.17 and 1.4.x before 1.4.2 allows remote attackers to cause a denial of service (crash) via a SIP INVITE message with an SDP containing one valid and one invalid IP address.
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Analysis
by VulDB Data Team • 01/20/2025
The vulnerability identified as CVE-2007-1561 represents a critical denial of service weakness within the Asterisk telephony platform that affects versions prior to 1.2.17 and 1.4.x before 1.4.2. This issue specifically targets the channel driver component responsible for handling Session Initiation Protocol communications, making it particularly dangerous for organizations relying on VoIP infrastructure for their communication systems. The vulnerability stems from insufficient input validation mechanisms within the SDP parsing functionality that processes session descriptions accompanying SIP INVITE messages. When a malicious actor crafts a SIP INVITE containing an SDP with one valid and one invalid IP address, the Asterisk system fails to properly handle this malformed data structure, leading to a complete system crash and subsequent denial of service for legitimate users.
The technical flaw manifests in the channel driver's inability to gracefully handle mixed valid and invalid IP addresses within SDP attributes during SIP session establishment. This condition creates a memory corruption scenario where the system attempts to process the invalid IP address while maintaining references to the valid one, resulting in unpredictable behavior that ultimately causes the Asterisk daemon to terminate unexpectedly. The vulnerability operates at the protocol parsing layer where SIP messages are interpreted and processed, making it particularly effective as a remote attack vector since no authentication or local access is required to exploit the flaw. The specific nature of the attack requires crafting a carefully constructed SIP INVITE message that includes an SDP with malformed address information, which then triggers an unhandled exception in the Asterisk processing pipeline.
From an operational impact perspective, this vulnerability poses significant risks to organizations dependent on Asterisk for their voice communication infrastructure, potentially disrupting critical business operations and communication channels. The remote exploitation capability means that attackers can target systems from outside the network perimeter without requiring any credentials or privileged access, making it an attractive vector for service disruption attacks. The crash effect completely terminates the Asterisk service, requiring manual intervention to restart the system and restore normal communication capabilities, which can result in extended downtime for organizations relying on VoIP services. This vulnerability aligns with CWE-129, which describes improper validation of input ranges, and specifically demonstrates how malformed data handling can lead to system instability and service disruption.
Organizations should implement immediate mitigation strategies including applying the vendor-provided patches for versions 1.2.17 and 1.4.2, which contain fixes for the SDP parsing logic. Network-level protections such as SIP message filtering and rate limiting can help reduce the effectiveness of such attacks by blocking malformed INVITE messages before they reach the Asterisk system. Additionally, implementing intrusion detection systems that monitor for suspicious SIP traffic patterns can provide early warning of potential exploitation attempts. The remediation approach should follow ATT&CK technique T1499.004, which focuses on avoiding or mitigating denial of service attacks by implementing proper input validation and error handling mechanisms. Regular security assessments and vulnerability scanning should be conducted to identify any remaining exposure points and ensure that the patched systems maintain their integrity against similar vulnerabilities in the future.