CVE-2023-6174 Overview
CVE-2023-6174 is a denial of service vulnerability in Wireshark's SSH dissector that affects versions 4.0.0 through 4.0.10. The vulnerability allows attackers to crash Wireshark through packet injection or by providing a specially crafted capture file. This out-of-bounds read vulnerability (CWE-125) combined with injection issues (CWE-74) can disrupt network analysis operations and potentially be leveraged to interrupt security monitoring activities.
Critical Impact
Network security analysts and administrators using vulnerable Wireshark versions may experience application crashes when analyzing SSH traffic, potentially leading to gaps in network visibility and disrupted incident response activities.
Affected Products
- Wireshark versions 4.0.0 to 4.0.10
- Debian Linux 12.0
- Various Linux distributions including Fedora and Gentoo
Discovery Timeline
- 2023-11-16 - CVE-2023-6174 published to NVD
- 2024-11-21 - Last updated in NVD database
Technical Details for CVE-2023-6174
Vulnerability Analysis
The vulnerability resides in Wireshark's SSH dissector component, which is responsible for parsing and analyzing SSH protocol traffic in packet captures. When processing malformed SSH packets, the dissector fails to properly validate input boundaries, resulting in an out-of-bounds read condition. This memory safety violation can trigger an application crash, causing a denial of service condition.
The attack requires user interaction in that an analyst must either capture malicious network traffic or open a crafted capture file. The vulnerability does not require authentication and can be exploited remotely through packet injection on a network being monitored by a vulnerable Wireshark instance.
Root Cause
The root cause of this vulnerability is improper input validation in the SSH dissector code (CWE-125: Out-of-bounds Read combined with CWE-74: Improper Neutralization of Special Elements in Output Used by a Downstream Component). The dissector does not adequately verify the bounds of data structures when parsing SSH protocol fields, allowing specially crafted packets to trigger memory access violations outside allocated buffer boundaries.
Attack Vector
The attack can be executed through two primary vectors:
Packet Injection: An attacker on the same network segment can inject malicious SSH packets that will be captured and parsed by Wireshark, causing it to crash when the SSH dissector processes the crafted data.
Crafted Capture File: An attacker can create a malicious pcap/pcapng file containing the crafted SSH packets and distribute it to targets. When an analyst opens this file in a vulnerable Wireshark version, the application crashes.
The vulnerability manifests when the SSH dissector encounters specially crafted packet data that causes it to read beyond allocated memory boundaries. For detailed technical information, refer to the GitLab Issue #19369 and the Wireshark Security Advisory.
Detection Methods for CVE-2023-6174
Indicators of Compromise
- Unexpected Wireshark application crashes when analyzing SSH traffic or opening capture files
- Crash reports indicating memory access violations in the SSH dissector module
- Suspicious pcap/pcapng files with malformed SSH protocol data received from external sources
- Network captures containing unusually structured SSH packets from unexpected sources
Detection Strategies
- Monitor for Wireshark process crashes and analyze crash dumps for SSH dissector-related memory violations
- Implement file integrity monitoring for capture files received from external parties
- Review system logs for repeated Wireshark termination events correlating with network capture activities
- Use SentinelOne's Singularity XDR to detect anomalous process termination patterns for network analysis tools
Monitoring Recommendations
- Configure crash reporting mechanisms to alert security teams when Wireshark terminates unexpectedly
- Establish baselines for normal Wireshark operation and alert on deviations
- Monitor network traffic for SSH packets with anomalous field lengths or structures that could indicate exploitation attempts
- Implement endpoint detection capabilities to identify potential denial of service attacks targeting analysis tools
How to Mitigate CVE-2023-6174
Immediate Actions Required
- Upgrade Wireshark to version 4.0.11 or later immediately
- Avoid opening capture files from untrusted sources until patched
- Consider disabling the SSH dissector temporarily if upgrade is not immediately possible
- Review and validate the source of any pcap files before analysis
Patch Information
Wireshark has released patches addressing this vulnerability. Users should upgrade to Wireshark version 4.0.11 or later to remediate this issue. Security advisories and patch information are available from the following sources:
Linux distribution users should apply available package updates through their respective package managers.
Workarounds
- Disable the SSH dissector if SSH protocol analysis is not required: Use the -d ssh option or disable via Analyze → Enabled Protocols menu
- Use network segmentation to isolate systems performing packet capture from potentially hostile networks
- Run Wireshark in an isolated environment (sandbox or virtual machine) when analyzing untrusted capture files
- Implement file scanning for capture files received from external sources before analysis
# Disable SSH dissector when running Wireshark from command line
wireshark -d ssh
# Alternatively, use tshark with disabled SSH dissector for automated analysis
tshark -d ssh -r capture.pcap
# Update Wireshark on Debian-based systems
sudo apt update && sudo apt upgrade wireshark
# Update Wireshark on Fedora
sudo dnf update wireshark
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
