CVE-2005-2081 in Asterisk
Summary
by MITRE
Stack-based buffer overflow in the function that parses commands in Asterisk 1.0.7, when the write = command option is enabled, allows remote attackers to execute arbitrary code via a command that has two double quotes followed by a tab character.
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Analysis
by VulDB Data Team • 07/09/2018
The vulnerability described in CVE-2005-2081 represents a critical stack-based buffer overflow within the Asterisk telephony application version 1.0.7. This flaw exists in the command parsing function that processes incoming commands when the write = command option is enabled, creating a significant security risk for systems utilizing this telephony platform. The vulnerability specifically manifests when processing commands containing two consecutive double quotes followed by a tab character, which triggers the buffer overflow condition in the application's memory management.
This buffer overflow vulnerability operates through a classic stack corruption mechanism where malicious input exceeds the allocated buffer space, overwriting adjacent memory locations including return addresses and function pointers. The exploitation occurs during command processing when the application fails to properly validate or limit the length of input strings before copying them into fixed-size buffers on the stack. The precise trigger condition of two double quotes followed by a tab character suggests that the parsing logic mishandles escape sequences or string termination characters, leading to improper buffer boundary calculations.
The operational impact of this vulnerability extends beyond simple privilege escalation to full system compromise, as remote attackers can execute arbitrary code with the privileges of the Asterisk process. This creates a severe threat landscape where unauthorized individuals can gain control over telephony systems, potentially leading to call interception, unauthorized access to communication networks, or further exploitation of the compromised system. The vulnerability affects systems where the write = command option is enabled, which is a common configuration in telephony applications requiring command logging or debugging capabilities. Systems utilizing Asterisk for voice over IP communications, PBX implementations, or telephony gateways become particularly vulnerable when this configuration is active.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security hardening. The primary recommendation involves upgrading to a patched version of Asterisk that resolves the buffer overflow condition in the command parsing function, which aligns with industry best practices for vulnerability management and patch deployment. Additionally, administrators should disable the write = command option when not actively required for debugging purposes, as this eliminates the attack surface for this specific vulnerability. Network segmentation and access controls should be implemented to limit exposure of Asterisk systems to untrusted networks, while implementing input validation measures to prevent malformed command sequences from reaching the vulnerable parsing functions. This vulnerability demonstrates the importance of proper input validation and buffer management in telephony applications, reflecting common security weaknesses categorized under CWE-121 Stack-based Buffer Overflow and aligning with ATT&CK techniques related to code injection and privilege escalation through application vulnerabilities.