CVE-2007-4455 in Asterisk
Summary
by MITRE
The SIP channel driver (chan_sip) in Asterisk Open Source 1.4.x before 1.4.11, AsteriskNOW before beta7, Asterisk Appliance Developer Kit 0.x before 0.8.0, and s800i (Asterisk Appliance) 1.x before 1.0.3 allows remote attackers to cause a denial of service (memory exhaustion) via a SIP dialog that causes a large number of history entries to be created.
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Analysis
by VulDB Data Team • 12/24/2017
The vulnerability described in CVE-2007-4455 represents a critical denial of service weakness within the SIP channel driver component of Asterisk Open Source telephony platform. This flaw specifically affects versions 1.4.x prior to 1.4.11 and related products including AsteriskNOW beta6 and earlier, Asterisk Appliance Developer Kit 0.x prior to 0.8.0, and s800i Asterisk Appliance 1.x prior to 1.0.3. The vulnerability stems from inadequate memory management within the SIP dialog handling mechanism, where maliciously crafted SIP dialog sequences can trigger excessive memory allocation that ultimately leads to system resource exhaustion.
The technical implementation of this vulnerability resides in the chan_sip channel driver's handling of SIP dialog state tracking and history management. When a SIP dialog is established and maintained, the system maintains a history of dialog states and related metadata for tracking purposes. The flaw occurs when an attacker sends a sequence of SIP messages that causes the system to create an excessive number of history entries without proper bounds checking or memory cleanup mechanisms. This results in a gradual consumption of available memory resources until the system becomes unresponsive or crashes entirely.
From an operational perspective, this vulnerability presents a significant risk to telephony infrastructure deployments that rely on Asterisk for voice communication services. Attackers can exploit this weakness by initiating a SIP dialog with specific parameters that cause the system to continuously create new history entries. The impact extends beyond simple service disruption as the memory exhaustion can affect the entire telephony system, potentially causing cascading failures in call routing, registration handling, and other critical telephony functions. The vulnerability is particularly dangerous in environments where Asterisk serves as a core communication platform for businesses, call centers, or unified communications systems.
The root cause of this vulnerability aligns with CWE-400, which categorizes improper resource management as a fundamental weakness in software design. This weakness allows attackers to exhaust system resources through controlled input sequences that trigger excessive memory allocation. The attack vector is classified as remote, meaning an attacker does not need physical access to the system, and can exploit the vulnerability from outside the network perimeter. The vulnerability also maps to ATT&CK technique T1499.004, which covers network denial of service attacks through resource exhaustion. Organizations should implement proper input validation and memory management practices, including setting limits on dialog history entries, implementing automatic cleanup mechanisms, and monitoring memory usage patterns to detect potential exploitation attempts.
Mitigation strategies for this vulnerability include immediate patching of affected systems to versions 1.4.11 and later, which contain proper memory management fixes for the SIP dialog handling. Network-level protections such as rate limiting for SIP registration and call setup messages can help reduce the impact of exploitation attempts. Additionally, implementing memory monitoring and alerting systems allows administrators to detect unusual memory consumption patterns that may indicate exploitation. Regular security assessments of telephony infrastructure should include vulnerability scanning for similar resource exhaustion issues in other components of the communication stack. The fix implemented in the patched versions addresses the core memory management issue by introducing proper bounds checking for dialog history entries and implementing automatic cleanup mechanisms to prevent indefinite memory growth during SIP dialog processing.