CVE-2012-1183 in Asterisk
Summary
by MITRE
Stack-based buffer overflow in the milliwatt_generate function in the Miliwatt application in Asterisk 1.4.x before 1.4.44, 1.6.x before 1.6.2.23, 1.8.x before 1.8.10.1, and 10.x before 10.2.1, when the o option is used and the internal_timing option is off, allows remote attackers to cause a denial of service (application crash) via a large number of samples in an audio packet.
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Analysis
by VulDB Data Team • 03/22/2021
The vulnerability described in CVE-2012-1183 represents a critical stack-based buffer overflow affecting the Asterisk telephony application across multiple version lines. This flaw exists within the milliwatt_generate function, which is responsible for processing audio packets containing milliwatt measurements during telephony operations. The vulnerability specifically manifests when the o option is enabled in conjunction with the internal_timing option being disabled, creating a dangerous condition where malformed audio data can trigger memory corruption. The attack vector involves remote exploitation through carefully crafted audio packets containing an excessive number of samples that exceed the allocated stack buffer space. This type of vulnerability falls under CWE-121, which categorizes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent stack memory locations. The operational impact of this vulnerability extends beyond simple denial of service, as the application crash can be leveraged to disrupt critical telephony services and potentially provide a foothold for further exploitation.
The technical implementation of this vulnerability demonstrates a classic stack buffer overflow where the milliwatt_generate function fails to properly validate the size of incoming audio packet data before copying it into a fixed-size stack buffer. When the o option is specified and internal_timing is disabled, the application enters a processing path that does not adequately sanitize the sample count within audio packets. Attackers can construct malicious audio packets containing an excessive number of samples that surpass the predetermined buffer limits, causing the stack to overflow and overwrite adjacent memory regions including return addresses and function parameters. This memory corruption directly leads to application instability and subsequent crash, effectively creating a denial of service condition that can be exploited remotely without authentication. The vulnerability's presence across multiple Asterisk version lines indicates a fundamental flaw in the codebase that persisted through several releases, suggesting inadequate code review processes and potentially insufficient input validation mechanisms. From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.004, which involves network disruption through application or service availability attacks, and represents a classic example of how improper input handling can lead to system instability.
The exploitation of CVE-2012-1183 has significant operational implications for organizations relying on Asterisk for voice communications, particularly in enterprise environments where telephony infrastructure is critical for business operations. The vulnerability can be triggered by any remote attacker who can send audio packets to the affected Asterisk server, making it particularly dangerous in networked environments where such packets might be transmitted through legitimate telephony channels. Organizations using affected Asterisk versions face potential disruption of voice services, call failures, and possible cascading effects on dependent systems that rely on telephony connectivity. The vulnerability's remediation requires immediate patching of affected Asterisk installations to versions that include proper bounds checking and input validation for the milliwatt_generate function. Security teams should implement network monitoring to detect unusual audio packet patterns that might indicate exploitation attempts, while also ensuring proper access controls and network segmentation to limit potential attack surfaces. The vulnerability serves as a reminder of the critical importance of input validation in telephony applications and highlights the need for robust security testing throughout the software development lifecycle to prevent similar issues from persisting across multiple software releases.