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The CVE-2022-26373 vulnerability stems from a flawed string comparison within the basic authentication mechanism for the proxy feature. The access control check uses a short-circuiting logical OR operation (||) to compare the provided `user` and `pass` against the stored credentials (proxy.basicAuth.Username and proxy.basicAuth.Password). This type of comparison is vulnerable to a timing attack because the operation exits early upon the first non-matching character. An attacker can exploit this by systematically sending requests with progressively longer password guesses. By meticulously measuring the server’s response time for each attempt, the attacker can infer character correctness. A longer response time indicates that more characters were compared correctly before a mismatch was found, allowing the attacker to brute-force the password one character at a time through statistical analysis of timing differences.
Platform: Dragonfly
Version: <2.1.0
Vulnerability: Timing Attack
Severity: Critical
date: 2022-03-22
Prediction: 2022-03-29
What Undercode Say:
Script to demonstrate timing attack concept
for char in {a..z} {A..Z} {0..9}; do
start=$(date +%s%N)
curl -s -o /dev/null -w "%{http_code}" -u "admin:guess$char" http://vulnerable-host/proxy
end=$(date +%s%N)
echo "Char: $char, Time: $((end-start))"
done
// Vulnerable Code Snippet
if user != proxy.basicAuth.Username || pass != proxy.basicAuth.Password {
return Unauthorized
}
// Patched Code using constant-time comparison
if !constantTimeCompare(user, proxy.basicAuth.Username) || !constantTimeCompare(pass, proxy.basicAuth.Password) {
return Unauthorized
}
How Exploit:
Measure response timings for sequential character guesses to statistically deduce the correct proxy authentication password.
Protection from this CVE
Upgrade to Dragonfly version 2.1.0 or later, which implements constant-time comparison functions for authentication checks.
Impact:
Full proxy authentication bypass potential, leading to unauthorized access and control of the proxy feature.
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Sources:
Reported By: github.com
Extra Source Hub:
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