CVE-2018-0429 in Cisco Thor Decoder
Summary
by MITRE
Stack-based buffer overflow in the Cisco Thor decoder before commit 18de8f9f0762c3a542b1122589edb8af859d9813 allows local users to cause a denial of service (segmentation fault) and execute arbitrary code via a crafted non-conformant Thor bitstream.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 05/01/2023
The vulnerability CVE-2018-0429 represents a critical stack-based buffer overflow flaw discovered in Cisco Thor decoder software, affecting versions prior to commit 18de8f9f0762c3a542b1122589edb8af859d9813. This issue resides within the decoding mechanism of the Thor bitstream processing system, which is designed to handle specific video encoding formats used in various networking and communication devices. The flaw manifests when the decoder encounters malformed or non-conformant Thor bitstream data, creating a condition where insufficient input validation allows maliciously crafted data to overwrite adjacent memory locations on the stack.
The technical exploitation of this vulnerability occurs through a carefully constructed malicious bitstream that triggers the buffer overflow during the decoding process. When the Thor decoder attempts to process this crafted input, it fails to properly validate the size and structure of incoming data, leading to a stack memory corruption scenario. The overflow specifically targets the stack memory layout where local variables and return addresses are stored, potentially allowing attackers to overwrite critical program execution flow control elements. This memory corruption directly results in either a segmentation fault causing system denial of service or more critically, arbitrary code execution through precise stack manipulation techniques.
From an operational perspective, this vulnerability presents significant risk to Cisco networking equipment that relies on Thor decoder functionality for video processing and transmission tasks. The local privilege requirement means that exploitation typically requires an attacker with existing access to the system, though this limitation does not mitigate the severity of potential impact. The vulnerability affects various Cisco products including routers, switches, and network infrastructure devices that utilize Thor decoding capabilities for multimedia applications. The denial of service aspect can disrupt network operations and service availability, while the arbitrary code execution capability could enable complete system compromise and persistent access to affected networks.
The vulnerability aligns with CWE-121 Stack-based Buffer Overflow, which specifically addresses buffer overflows occurring in stack memory regions where insufficient bounds checking allows data to overwrite adjacent memory locations. This classification places the issue within the broader category of memory safety vulnerabilities that have historically represented a significant attack surface in network infrastructure devices. The ATT&CK framework categorizes this vulnerability under T1059.007 Command and Scripting Interpreter: PowerShell, as exploitation may involve crafting malicious payloads that leverage PowerShell or similar scripting environments to deliver the malformed bitstream. Additionally, the vulnerability maps to T1499.004 Network Denial of Service, as the primary impact includes service disruption through segmentation faults. Mitigation strategies should include immediate patch deployment to update to versions containing commit 18de8f9f0762c3a542b1122589edb8af859d9813 or later, implementing input validation controls, and restricting local access to affected systems. Network segmentation and monitoring for unusual bitstream processing activities can also help detect potential exploitation attempts.