CVE-2017-9345 in Wireshark
Summary
by MITRE
In Wireshark 2.2.0 to 2.2.6 and 2.0.0 to 2.0.12, the DNS dissector could go into an infinite loop. This was addressed in epan/dissectors/packet-dns.c by trying to detect self-referencing pointers.
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Analysis
by VulDB Data Team • 12/07/2022
The vulnerability identified as CVE-2017-9345 represents a critical denial of service weakness in Wireshark network protocol analyzer versions 2.2.0 through 2.2.6 and 2.0.0 through 2.0.12. This flaw specifically affects the DNS dissector component responsible for interpreting and displaying DNS protocol data within captured network traffic. The issue manifests as an infinite loop condition that can cause Wireshark to become unresponsive or consume excessive system resources when processing specially crafted DNS packets. The vulnerability stems from insufficient validation of DNS pointer references within the packet dissection logic, creating a scenario where the dissector can recursively follow pointers that reference themselves, leading to endless processing cycles. This type of vulnerability falls under CWE-835, which addresses the weakness of infinite loops or recursive calls without proper termination conditions, making it particularly dangerous in network analysis tools where analysts process potentially malicious traffic. The ATT&CK framework categorizes this under T1499.004, specifically targeting the denial of service technique through resource exhaustion, as the infinite loop consumes CPU cycles and memory resources indefinitely.
The technical implementation of this vulnerability occurs within the epan/dissectors/packet-dns.c file where the DNS dissector processes DNS packet structures containing pointer fields. DNS protocol utilizes compression mechanisms to reduce packet size by allowing pointers to reference previously transmitted data within the same packet. When a pointer references itself or creates a circular reference, the dissector's parsing logic enters an infinite loop attempting to resolve these self-referencing pointers. This occurs because the dissection algorithm lacks proper cycle detection mechanisms to identify when a pointer has already been processed or when it creates a recursive loop. The flaw demonstrates a classic example of inadequate input validation and insufficient state tracking in protocol parsing components, where the system fails to recognize when it has encountered a previously processed reference. The vulnerability is particularly insidious because it can be triggered by simply opening a maliciously crafted pcap file containing such malformed DNS packets, requiring no special privileges or complex attack vectors.
The operational impact of CVE-2017-9345 extends beyond simple service disruption to potentially compromise the entire network analysis workflow. When exploited, this vulnerability can cause Wireshark to become unresponsive for extended periods, forcing analysts to terminate the application manually and potentially lose valuable analysis data. In enterprise environments where network troubleshooting relies heavily on Wireshark, this denial of service condition can significantly impact incident response capabilities and network monitoring operations. The vulnerability affects both interactive analysis and automated processing scenarios, meaning that even batch processing of network captures can be brought to a halt by a single malicious packet. System administrators and network security professionals who regularly analyze network traffic are particularly at risk since they may unknowingly open compromised capture files, leading to system resource exhaustion and potential denial of service for other network analysis tasks. The vulnerability also impacts automated security tools that depend on Wireshark for packet analysis, potentially causing cascading failures in security infrastructure.
The remediation for CVE-2017-9345 was implemented through a targeted fix in the packet-dns.c file that introduced proper cycle detection mechanisms within the DNS dissector. The solution involves adding logic to track previously visited pointer positions and detect when a pointer references a location that has already been processed, thereby preventing the infinite loop condition. This fix aligns with industry best practices for protocol parsing and input validation, ensuring that recursive or circular references are properly handled without causing system resource exhaustion. The implementation follows established security principles for defensive programming and demonstrates the importance of proper state management in network protocol analysis tools. Organizations should immediately update to Wireshark versions 2.2.7 or 2.0.13 and later, which contain the patched dissector code. Additionally, network security teams should implement monitoring for suspicious packet patterns and consider implementing network segmentation to limit the impact of potentially malicious traffic. The vulnerability serves as a reminder of the critical importance of input validation and cycle detection in protocol parsers, particularly in security tools that process untrusted network data.