CVE-2023-27785 – CVE-2023-27785 is a NULL pointer dereference vu... (How to Fix)

Q: What is the severity of CVE-2023-27785?

CVE-2023-27785 has a CVSS score of 7.5 (HIGH). CVE-2023-27785 is a NULL pointer dereference vulnerability in TCPreplay's tcprep utility that allows remote attackers to cause denial of service through the parse endpoints function. This affects users who process untrusted network traffic with TCPreplay v4.4.3. The vulnerability can crash the tcprep process when parsing maliciously crafted input.

📋 TL;DR

CVE-2023-27785 is a NULL pointer dereference vulnerability in TCPreplay's tcprep utility that allows remote attackers to cause denial of service through the parse endpoints function. This affects users who process untrusted network traffic with TCPreplay v4.4.3. The vulnerability can crash the tcprep process when parsing maliciously crafted input.

💻 Affected Systems

Products:

TCPreplay tcprep

Versions: v4.4.3 (specifically mentioned in CVE)

Operating Systems: Linux, Unix-like systems where TCPreplay is commonly used

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects the tcprep utility component of TCPreplay, not other TCPreplay tools. Vulnerability triggers when parsing endpoints from input traffic files.

📦 What is this software?

Tcpreplay by Broadcom

View all CVEs affecting Tcpreplay →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete denial of service for TCPreplay processing operations, potentially disrupting network testing, analysis, or replay workflows that depend on tcprep.

🟠

Likely Case

Application crash when processing malicious network traffic, requiring manual restart of tcprep processes and potentially corrupting in-progress work.

🟢

If Mitigated

Minimal impact if tcprep only processes trusted traffic sources or runs in isolated environments with proper monitoring.

🌐 Internet-Facing: LOW - tcprep is typically used offline for network traffic analysis/replay rather than as an internet-facing service.

🏢 Internal Only: MEDIUM - Internal users could exploit if they can feed malicious traffic files to tcprep, potentially disrupting network testing operations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW - Requires ability to provide malicious input to tcprep's parse endpoints function.

Exploitation requires feeding specially crafted traffic data to tcprep. No authentication needed if user has access to run tcprep with malicious input.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: TCPreplay versions after v4.4.3

Vendor Advisory: https://github.com/appneta/tcpreplay/issues/785

Restart Required: Yes

Instructions:

1. Check current TCPreplay version with 'tcpreplay --version'. 2. Update TCPreplay using your distribution's package manager (apt, yum, etc.) or compile from source. 3. Verify update with 'tcpreplay --version' again. 4. Restart any processes using tcprep.

🔧 Temporary Workarounds

Input Validation and Sandboxing

all

Only process trusted traffic files with tcprep and run in isolated environments

Process Monitoring and Restart

linux

Implement monitoring to detect and restart crashed tcprep processes

# Example using systemd service with Restart=always
[Service]
Restart=always
RestartSec=5

🧯 If You Can't Patch

Restrict tcprep usage to trusted users only and audit access controls
Implement strict input validation - only allow tcprep to process traffic files from trusted sources

🔍 How to Verify

Check if Vulnerable:

Run 'tcpreplay --version' and check if output shows v4.4.3. Also check package manager for installed version.

Check Version:

tcpreplay --version

Verify Fix Applied:

After update, confirm version is newer than v4.4.3 with 'tcpreplay --version'. Test with known safe traffic files to ensure functionality.

📡 Detection & Monitoring

Log Indicators:

Segmentation fault or crash logs from tcprep process
Unexpected termination of tcprep with error codes

Network Indicators:

Unusual traffic patterns if tcprep is part of automated testing pipeline

SIEM Query:

process.name:"tcprep" AND (event.type:"crash" OR exit_code:139)

📊 Metadata

CVE ID: CVE-2023-27785

CVSS v3 Score: 7.5 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE: CWE-476

Published: March 16, 2023

Last Updated: February 26, 2025

🔗 References

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