CVE-2006-1827 in Asterisk
Summary
by MITRE
Integer signedness error in format_jpeg.c in Asterisk 1.2.6 and earlier allows remote attackers to execute arbitrary code via a length value that passes a length check as a negative number, but triggers a buffer overflow when it is used as an unsigned length.
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Analysis
by VulDB Data Team • 06/18/2019
The vulnerability described in CVE-2006-1827 represents a critical integer signedness error within the Asterisk telephony application's JPEG format handling component. This flaw exists in the format_jpeg.c file of Asterisk versions 1.2.6 and earlier, where the application fails to properly validate the signedness of length parameters during JPEG image processing operations. The vulnerability stems from a fundamental mismatch between how signed and unsigned integers are handled in memory operations, creating a pathway for malicious code execution through crafted JPEG data.
The technical implementation of this vulnerability exploits a specific condition where a negative signed integer value passes an initial length validation check, which is designed to verify that image data does not exceed predetermined limits. However, when this negative value is subsequently cast or interpreted as an unsigned integer for buffer allocation purposes, it results in an unexpectedly large numerical value that exceeds the bounds of the allocated memory buffer. This conversion from signed to unsigned representation causes the application to allocate insufficient memory for the buffer, leading to a classic buffer overflow condition that can be exploited to overwrite adjacent memory locations.
From an operational perspective, this vulnerability presents a severe risk to telephony systems running affected versions of Asterisk, as remote attackers can leverage this flaw to execute arbitrary code on the target system. The attack vector requires the attacker to send a specially crafted JPEG image file to a vulnerable Asterisk server, typically through SIP or other telephony protocols that support image transmission. The successful exploitation can result in complete system compromise, allowing attackers to gain unauthorized access, execute malicious commands, or potentially escalate privileges within the telephony infrastructure. This vulnerability directly impacts the confidentiality, integrity, and availability of telephony services, making it particularly dangerous for enterprise communication systems.
The vulnerability aligns with CWE-195: Signed to Unsigned Conversion Error, which specifically addresses the risks associated with converting signed integers to unsigned types without proper validation. This flaw also maps to several ATT&CK techniques including T1059.007: Command and Scripting Interpreter: Python and T1068: Exploitation for Privilege Escalation, as the buffer overflow can be leveraged to execute arbitrary code and potentially gain elevated system privileges. Organizations using Asterisk should implement immediate mitigations including upgrading to patched versions of the software, implementing network segmentation to restrict access to telephony services, and deploying intrusion detection systems to monitor for suspicious JPEG data transfers. Additionally, input validation controls should be strengthened to ensure proper bounds checking on all image file parameters, and regular security audits should be conducted to identify similar signedness issues in other components of the telephony infrastructure.