CVE-2022-31055
📋 TL;DR
CVE-2022-31055 is a security misconfiguration vulnerability in kCTF (Kubernetes CTF infrastructure) where the 'kctf cluster set-src-ip-ranges' command failed to properly restrict traffic, allowing connections from any IP address. This affects kCTF deployments prior to version 1.6.0, potentially exposing CTF challenges to unauthorized access.
💻 Affected Systems
- kCTF (Kubernetes CTF infrastructure)
📦 What is this software?
Kctf by Google
⚠️ Risk & Real-World Impact
Worst Case
Unauthorized attackers could access and potentially compromise CTF challenge infrastructure, leading to data exposure, challenge manipulation, or lateral movement within the Kubernetes cluster.
Likely Case
Unauthorized access to CTF challenges intended to be private, potentially allowing challenge solutions to be leaked or bypassing intended access controls.
If Mitigated
If proper network segmentation and access controls are implemented, impact is limited to the specific kCTF namespace and challenges.
🎯 Exploit Status
Exploitation requires network access to the kCTF cluster; the vulnerability is a configuration bypass rather than a code execution flaw.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.6.0
Vendor Advisory: https://github.com/google/kctf/security/advisories/GHSA-4g2v-6qc6-6jv5
Restart Required: Yes
Instructions:
1. Update kCTF to version 1.6.0 or later. 2. Redeploy affected clusters. 3. Verify IP restrictions are properly enforced.
🔧 Temporary Workarounds
Mark challenges as private and use port-forwarding
allSet challenges to 'public: false' and use kctf debug port-forward for authorized access
kubectl edit challenge [challenge-name] # Set public: false
kctf chal debug port-forward [challenge-name]
🧯 If You Can't Patch
- Implement network-level IP restrictions using Kubernetes Network Policies or firewall rules
- Isolate kCTF clusters from untrusted networks and implement strict ingress controls
🔍 How to Verify
Check if Vulnerable:
Check kCTF version and verify if IP restrictions are being properly enforced by testing from unauthorized IP addressesCheck Version:
kctf versionVerify Fix Applied:
Confirm kCTF version is 1.6.0+ and test that IP restrictions now properly block unauthorized traffic📡 Detection & Monitoring
Log Indicators:
- Unexpected connections to kCTF services from unauthorized IP ranges
- Failed IP restriction enforcement logs
Network Indicators:
- Traffic to kCTF services bypassing expected IP restrictions
- Connection attempts from unexpected geographical locations
SIEM Query:
source_ip NOT IN (allowed_ip_ranges) AND destination_port IN (kctf_ports)🔗 References
- https://github.com/google/kctf/commit/8cf050be974fcc2fd8aa136701f9a66f2b2a5202
- https://github.com/google/kctf/pull/371
- https://github.com/google/kctf/security/advisories/GHSA-4g2v-6qc6-6jv5
- https://github.com/google/kctf/commit/8cf050be974fcc2fd8aa136701f9a66f2b2a5202
- https://github.com/google/kctf/pull/371
- https://github.com/google/kctf/security/advisories/GHSA-4g2v-6qc6-6jv5
