CVE-2023-27789 – A vulnerability in TCPprep v.4.4.3 allows remot... (How to Fix)

Q: What is the severity of CVE-2023-27789?

CVE-2023-27789 has a CVSS score of 7.5 (HIGH). A vulnerability in TCPprep v.4.4.3 allows remote attackers to cause denial of service via the cidr2cidr function. This affects systems running vulnerable versions of TCPprep, particularly those processing untrusted network traffic. The issue stems from improper handling of certain inputs leading to application crashes.

📋 TL;DR

A vulnerability in TCPprep v.4.4.3 allows remote attackers to cause denial of service via the cidr2cidr function. This affects systems running vulnerable versions of TCPprep, particularly those processing untrusted network traffic. The issue stems from improper handling of certain inputs leading to application crashes.

💻 Affected Systems

Products:

TCPprep

Versions: v.4.4.3 specifically mentioned; earlier versions may also be affected

Operating Systems: Linux, Unix-like systems where TCPprep runs

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems where TCPprep is installed and processing network traffic. The vulnerability is triggered through the cidr2cidr function.

📦 What is this software?

Tcpreplay by Broadcom

View all CVEs affecting Tcpreplay →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete service disruption of TCPprep functionality, potentially affecting network testing or traffic replay operations that depend on it.

🟠

Likely Case

Application crash when processing maliciously crafted network traffic, requiring manual restart of TCPprep processes.

🟢

If Mitigated

Minimal impact if TCPprep is not exposed to untrusted traffic sources or if input validation is implemented.

🌐 Internet-Facing: MEDIUM - TCPprep is typically used for internal network testing but could be exposed if misconfigured.

🏢 Internal Only: MEDIUM - Internal attackers or compromised systems could exploit this to disrupt network testing operations.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

The vulnerability appears to be triggered remotely without authentication. The GitHub references show the issue was reported and fixed, suggesting exploit details may be available to researchers.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in versions after v.4.4.3; check latest TCPprep releases

Vendor Advisory: https://github.com/appneta/tcpreplay/issues/784

Restart Required: Yes

Instructions:

1. Check current TCPprep version. 2. Update to latest version from official repository. 3. Restart any TCPprep processes or services.

🔧 Temporary Workarounds

Input validation wrapper

linux

Implement input validation for cidr2cidr function calls to filter malicious inputs

# Custom script to validate CIDR inputs before passing to TCPprep

Network isolation

linux

Restrict network access to TCPprep instances to trusted sources only

iptables -A INPUT -p tcp --dport [TCPprep_port] -s [trusted_ip] -j ACCEPT
iptables -A INPUT -p tcp --dport [TCPprep_port] -j DROP

🧯 If You Can't Patch

Isolate TCPprep instances from untrusted networks using firewall rules
Monitor TCPprep processes for crashes and implement automatic restart mechanisms

🔍 How to Verify

Check if Vulnerable:

Check TCPprep version: tcpreplay --version | grep 'version'

Check Version:

tcpreplay --version

Verify Fix Applied:

Verify version is newer than 4.4.3 and test cidr2cidr function with various inputs

📡 Detection & Monitoring

Log Indicators:

TCPprep process crashes
Segmentation fault errors in system logs
Abnormal termination of network testing processes

Network Indicators:

Unexpected traffic patterns to TCPprep ports
Multiple connection attempts followed by service unavailability

SIEM Query:

process_name='tcpreplay' AND (event_type='crash' OR exit_code=139)

📊 Metadata

CVE ID: CVE-2023-27789

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-617

Published: March 16, 2023

Last Updated: February 26, 2025

🔗 References

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