CVE-2016-10321
📋 TL;DR
This vulnerability in web2py allows remote attackers to bypass host-based access restrictions and perform brute-force password attacks against login systems. It affects web2py applications that use host-based access control lists. The flaw enables attackers to attempt unlimited password guesses even when their IP address should be blocked.
💻 Affected Systems
- web2py
📦 What is this software?
Web2py by Web2py
⚠️ Risk & Real-World Impact
Worst Case
Complete account takeover through brute-force attacks leading to unauthorized access, data theft, and potential privilege escalation within the application.
Likely Case
Successful brute-force attacks against weak passwords, resulting in unauthorized access to user accounts and potential data exposure.
If Mitigated
Limited impact with strong password policies, account lockouts, and network-level protections in place.
🎯 Exploit Status
The vulnerability is straightforward to exploit using automated tools. Public proof-of-concept code exists in the GitHub issue tracker.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.14.6 and later
Vendor Advisory: https://github.com/web2py/web2py/commit/944d8bd8f3c5cf8ae296fc03d149056c65358426
Restart Required: Yes
Instructions:
1. Backup your web2py application. 2. Update web2py to version 2.14.6 or later. 3. Restart the web2py application server. 4. Verify the fix by checking the version and testing access controls.
🔧 Temporary Workarounds
Implement Rate Limiting
allAdd application-level rate limiting for login attempts to prevent brute-force attacks.
# Implement in your web2py controller:
from gluon.tools import Recaptcha2
# Add rate limiting logic to login functions
Network-Level Blocking
linuxUse firewall rules or web application firewall to block suspicious IP addresses attempting multiple login attempts.
# Example iptables rule:
# iptables -A INPUT -p tcp --dport 80 -m recent --set --name web2py
# iptables -A INPUT -p tcp --dport 80 -m recent --update --seconds 60 --hitcount 10 --name web2py -j DROP
🧯 If You Can't Patch
- Implement strong password policies requiring complex passwords to reduce brute-force success probability.
- Deploy web application firewall with brute-force protection rules and monitor for suspicious login patterns.
🔍 How to Verify
Check if Vulnerable:
Check web2py version. If version is earlier than 2.14.6 and uses host-based access controls, the system is vulnerable.Check Version:
python web2py.py --versionVerify Fix Applied:
After updating to 2.14.6+, test that blocked hosts cannot attempt password verification. Verify version shows 2.14.6 or higher.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from same IP address
- Login attempts from IP addresses in deny lists
- Unusual login patterns outside normal hours
Network Indicators:
- High volume of POST requests to login endpoints
- Traffic patterns showing systematic password guessing
SIEM Query:
source="web2py" (event="login_failed" OR event="authentication_failure") | stats count by src_ip | where count > 10🔗 References
- https://github.com/web2py/web2py/commit/944d8bd8f3c5cf8ae296fc03d149056c65358426
- https://github.com/web2py/web2py/issues/1585#issuecomment-284317919
- https://usn.ubuntu.com/4030-1/
- https://github.com/web2py/web2py/commit/944d8bd8f3c5cf8ae296fc03d149056c65358426
- https://github.com/web2py/web2py/issues/1585#issuecomment-284317919
- https://usn.ubuntu.com/4030-1/
