Listen to this Post
Web cache deception is a vulnerability that allows attackers to trick a web cache into storing sensitive, dynamic content. This occurs due to discrepancies in how cache servers and origin servers process requests. A web cache sits between the origin server and users, storing responses based on predefined rules. Attackers manipulate these rules to expose private data.
How Web Cache Deception Works
- Cache Rules Mismatch: Caches often target static resources (e.g.,
.css,.js). - Malicious URL Crafting: An attacker tricks a victim into visiting a URL like
example.com/account.php/nonexistent.css. - Cache Misinterpretation: The cache treats the request as static (due to
.css) and stores the sensitive response. - Unauthorized Access: The attacker retrieves the cached response, gaining access to the victim’s private data.
You Should Know: Practical Exploitation & Defense
Exploiting Static Extension Cache Rules
Most CDNs cache files with common extensions. Test with:
curl -I http://example.com/profile.php/fake.css
Check if the response includes X-Cache: HIT, indicating cached content.
Testing with PortSwigger Labs
PortSwigger provides vulnerable labs for practice:
Mitigation Techniques
1. Disable Caching for Sensitive Pages:
<FilesMatch "\.(php|asp|jsp)$"> Header set Cache-Control "no-store" </FilesMatch>
2. Strict Path Validation:
location ~ .(css|js)$ {
if ($request_uri !~ "^/[a-z0-9]+.(css|js)$") {
return 403;
}
}
3. Cache Key Customization: Ensure cache keys include `Content-Type` and exclude ambiguous paths.
Linux Command for Cache Inspection
curl -v -H "Pragma: x-get-cache-key" http://example.com/account.php/fake.css
What Undercode Say
Web cache deception exploits poor cache configuration. Always:
- Validate cache rules rigorously.
- Use `no-store` for dynamic content.
- Monitor cache headers (
X-Cache,Cache-Control). - Test with tools like Burp Suite and custom scripts.
Expected Output:
HTTP/1.1 200 OK X-Cache: HIT Content-Type: text/html Cache-Control: public, max-age=3600
References:
Reported By: Asumanlukwago Web – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
