CVE-2023-2858: Wireshark NetScaler Parser DOS Vulnerability

CVE-2023-2858 Overview

CVE-2023-2858 is an out-of-bounds write vulnerability affecting the NetScaler file parser in Wireshark, a widely-used network protocol analyzer. The vulnerability allows remote attackers to cause a denial of service condition by crafting a malicious capture file that triggers a crash when opened or processed by vulnerable versions of Wireshark.

Critical Impact

Attackers can disrupt network analysis operations and potentially crash Wireshark instances across an organization by distributing malicious capture files, affecting incident response capabilities and network forensics workflows.

Affected Products

• Wireshark versions 4.0.0 to 4.0.5
• Wireshark versions 3.6.0 to 3.6.13
• Debian Linux 10.0 and 12.0 (via packaged Wireshark)

Discovery Timeline

• 2023-05-26 - CVE-2023-2858 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2023-2858

Vulnerability Analysis

This vulnerability is classified as CWE-787 (Out-of-Bounds Write), a memory corruption issue that occurs when the NetScaler file parser in Wireshark writes data past the boundaries of an allocated memory buffer. The vulnerability is triggered when Wireshark attempts to parse a specially crafted capture file in the NetScaler trace format.

The attack requires user interaction—a victim must open a malicious capture file. This could occur through various social engineering vectors, such as receiving a capture file via email for analysis, downloading one from a shared repository, or processing files from an untrusted source during incident response activities.

The primary impact is availability disruption. When exploited, the out-of-bounds write causes the Wireshark application to crash, terminating any ongoing packet analysis sessions. In environments where Wireshark is used for real-time network monitoring or forensic analysis, this could have significant operational implications.

Root Cause

The root cause is improper bounds checking in the NetScaler file parser component. When processing NetScaler trace files, the parser fails to properly validate input data lengths before writing to memory buffers. This allows a crafted file with malformed or unexpected data structures to trigger writes beyond allocated buffer boundaries, corrupting adjacent memory and causing the application to crash.

Attack Vector

The attack vector is network-based but requires user interaction. An attacker must convince a victim to open a malicious capture file. Common attack scenarios include:

Distributing malicious .cap or .pcap files disguised as legitimate network captures through email attachments, file-sharing platforms, or compromised repositories. Security researchers and network administrators who routinely analyze capture files from external sources are particularly at risk.

The vulnerability could also be exploited if Wireshark is configured to automatically process files from a monitored directory, or if integrated into automated analysis pipelines that process untrusted capture files.

Detection Methods for CVE-2023-2858

Indicators of Compromise

• Wireshark application crashes when opening capture files, particularly those in NetScaler trace format
• Unexpected process termination events for Wireshark (wireshark, tshark, or dumpcap) in system logs
• Presence of suspicious .cap, .pcap, or NetScaler trace files from untrusted sources
• Memory access violation errors in application crash dumps associated with Wireshark processes

Detection Strategies

• Monitor for abnormal Wireshark process termination patterns using endpoint detection tools
• Implement file integrity monitoring on directories where capture files are stored or processed
• Deploy SentinelOne's behavioral AI to detect anomalous application crashes and memory corruption indicators
• Use network security tools to scan email attachments and file transfers for known malicious capture file signatures

Monitoring Recommendations

• Enable application crash logging and configure alerts for repeated Wireshark crashes
• Monitor for unusual file access patterns involving capture files from external sources
• Implement SentinelOne Singularity XDR to correlate application crash events with potential file-based attack vectors
• Review logs for failed parsing attempts or error messages from the NetScaler dissector component

How to Mitigate CVE-2023-2858

Immediate Actions Required

• Update Wireshark to version 4.0.6 or later for the 4.x branch
• Update Wireshark to version 3.6.14 or later for the 3.6.x branch
• Apply operating system vendor patches for Debian Linux (DSA-5429 and related updates)
• Restrict opening capture files from untrusted or unknown sources until patching is complete

Patch Information

Wireshark has released security updates addressing this vulnerability. Detailed information is available in the Wireshark Security Notice WNPA-SEC-2023-15. The underlying issue is tracked in the Wireshark Issue Report.

Linux distributions have released corresponding patches:

• Debian: Security Advisory DSA-5429
• Gentoo: GLSA 202309-02

Organizations should prioritize updating Wireshark installations, particularly on systems used for network forensics and security analysis.

Workarounds

• Avoid opening capture files from untrusted or unknown sources until systems are patched
• Use isolated virtual machines or sandboxed environments when analyzing potentially malicious capture files
• Disable or restrict access to Wireshark on critical systems where network analysis tools are not required
• Consider using alternative network analysis tools temporarily for processing files from untrusted sources

# Check current Wireshark version
wireshark --version

# Update Wireshark on Debian-based systems
sudo apt update && sudo apt install --only-upgrade wireshark

# Update Wireshark on RHEL/CentOS systems
sudo yum update wireshark