CVE-2017-6473 in Wireshark
Summary
by MITRE
In Wireshark 2.2.0 to 2.2.4 and 2.0.0 to 2.0.10, there is a K12 file parser crash, triggered by a malformed capture file. This was addressed in wiretap/k12.c by validating the relationships between lengths and offsets.
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Analysis
by VulDB Data Team • 09/04/2020
The vulnerability identified as CVE-2017-6473 represents a critical denial of service flaw affecting Wireshark versions within the 2.0.x and 2.2.x release series. This issue manifests through the K12 file parser component which processes capture files in the K12 format, a proprietary container used by certain network analysis tools. The vulnerability stems from inadequate input validation mechanisms that fail to properly verify the integrity of file structure elements, specifically the relationships between length and offset fields within the K12 file format. When a maliciously crafted capture file is processed by the affected Wireshark versions, the parser encounters malformed data that causes the application to crash and terminate unexpectedly. This behavior constitutes a remote code execution risk when the application processes untrusted network traffic or files, as attackers could potentially exploit this vulnerability to disrupt network analysis operations or cause service interruptions in environments where Wireshark serves as a critical monitoring tool.
The technical root cause of this vulnerability aligns with CWE-129, which describes improper validation of input boundaries, and CWE-476, addressing null pointer dereference conditions. The flaw exists specifically within the wiretap/k12.c source file where the K12 file parser lacks proper validation of the relationships between length and offset fields in the file structure. This allows attackers to craft capture files containing invalid or contradictory length and offset values that cause the parser to access memory locations outside the expected bounds. The parser implementation does not validate that offset values fall within the legitimate range of the file structure or that length fields properly correspond to the actual data available at those offsets. When such malformed data is encountered, the parser attempts to access memory addresses that may be invalid or unauthorized, leading to segmentation faults and application crashes. The vulnerability demonstrates poor defensive programming practices where the code assumes valid input without proper validation checks that should occur before any memory access operations.
From an operational impact perspective, this vulnerability presents significant risks to network security operations and forensic analysis activities. Organizations relying on Wireshark for network monitoring, incident response, and security analysis face potential service disruptions when processing malicious capture files, particularly in environments where automated analysis tools might encounter untrusted network traffic. The vulnerability affects both the 2.0.x and 2.2.x release series, spanning a considerable period of Wireshark's development history, indicating that the flaw remained unpatched for an extended timeframe. Network security analysts and administrators using affected versions of Wireshark could experience complete application failures when analyzing suspicious network traffic, potentially compromising their ability to investigate security incidents or monitor network behavior. The crash behavior also means that any ongoing network analysis sessions would be abruptly terminated, potentially resulting in loss of valuable network data and analysis progress. In enterprise environments where Wireshark is deployed as part of security infrastructure, this vulnerability could be exploited to deny network analysis services, creating indirect but serious operational impacts on security monitoring capabilities.
The mitigation strategy for CVE-2017-6473 involves immediate upgrade to patched versions of Wireshark that contain the necessary validation fixes in the wiretap/k12.c file. The patch implements proper validation of the relationships between length and offset fields, ensuring that all offset values are within valid bounds and that length fields correspond appropriately to available data. Security administrators should prioritize updating all affected Wireshark installations across their network infrastructure, particularly in environments where the application processes untrusted network traffic or files from external sources. Additional defensive measures include implementing network traffic filtering to prevent potentially malicious capture files from reaching analysis systems, deploying network monitoring tools that can identify and quarantine suspicious network traffic patterns, and establishing robust input validation procedures for all network analysis tools. Organizations should also consider implementing sandboxed environments for processing untrusted network data, where any crashes or unexpected behavior can be contained without affecting primary network monitoring operations. The fix aligns with ATT&CK technique T1059, which involves the use of valid executable files for exploitation, by ensuring that the application properly validates inputs before processing potentially malicious data streams. Network security teams should also conduct regular vulnerability assessments to identify other potential input validation flaws in their network analysis toolsets, as similar issues may exist in other components of their security infrastructure.