CVE-2011-4063 in Asterisk
Summary
by MITRE
chan_sip.c in the SIP channel driver in Asterisk Open Source 1.8.x before 1.8.7.1 and 10.x before 10.0.0-rc1 does not properly initialize variables during request parsing, which allows remote authenticated users to cause a denial of service (daemon crash) via a malformed request.
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Analysis
by VulDB Data Team • 12/28/2024
The vulnerability identified as CVE-2011-4063 represents a critical flaw in the SIP channel driver component of Asterisk Open Source messaging platform. This issue affects versions prior to 1.8.7.1 in the 1.8.x series and 10.0.0-rc1 in the 10.x series, creating a significant risk for organizations relying on SIP-based communication infrastructure. The flaw manifests in the chan_sip.c module where variable initialization fails during the parsing of SIP requests, creating a condition that can be exploited by malicious actors to disrupt service availability.
The technical root cause of this vulnerability lies in improper variable initialization within the SIP request parsing logic. When authenticated users send malformed SIP requests to the affected Asterisk servers, the system fails to properly handle these requests due to uninitialized variables that are expected to contain critical parsing state information. This initialization failure leads to undefined behavior where the daemon process may attempt to access invalid memory locations or execute incorrect operations, ultimately resulting in a crash that terminates the SIP channel service.
From an operational perspective, this vulnerability presents a severe denial of service threat to voice communication systems that depend on Asterisk for SIP signaling. The attack requires only authenticated access to the system, which means that malicious actors with valid credentials or those who can obtain such credentials can trigger daemon crashes at will. This creates a situation where legitimate users may experience intermittent service disruptions, and in some cases, complete communication outages that can impact business operations, emergency services, or critical communication infrastructure.
The impact of this vulnerability aligns with CWE-457, which describes "Use of uninitialized variable" as a common software flaw that can lead to unpredictable behavior and system instability. From an adversarial standpoint, this vulnerability maps to ATT&CK technique T1499.004, "Endpoint Denial of Service," as it enables attackers to cause service disruption through malformed request processing. The vulnerability also demonstrates characteristics of T1566.002, "Phishing with Social Engineering," since attackers may exploit legitimate access credentials to gain the necessary authentication to trigger the flaw.
Organizations should implement immediate mitigation strategies including upgrading to patched versions of Asterisk that address this variable initialization issue. The recommended approach involves applying the official security patches released by the Asterisk development team, which properly initialize all variables during SIP request parsing operations. Additionally, network segmentation and access control measures should be implemented to limit the scope of potential exploitation, while monitoring systems should be deployed to detect unusual patterns of SIP request processing that may indicate attempted exploitation of this vulnerability.