CVE-2020-1742
📋 TL;DR
This vulnerability allows attackers with access to containers using nmstate/kubernetes-nmstate-handler to modify the /etc/passwd file and escalate privileges. It affects Kubernetes environments running the nmstate handler before version 2.3.0-30. Container-level access is required for exploitation.
💻 Affected Systems
- kubernetes-nmstate-handler
- nmstate
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full container compromise leading to host escape, lateral movement within the Kubernetes cluster, and potential control over the entire infrastructure.
Likely Case
Container privilege escalation allowing attackers to execute arbitrary commands, access sensitive data, and potentially pivot to other containers or nodes.
If Mitigated
Limited impact with proper container security controls, network segmentation, and least privilege principles in place.
🎯 Exploit Status
Requires existing access to the container; exploitation involves simple file modification techniques.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: kubernetes-nmstate-handler-container-v2.3.0-30 and later
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1803608
Restart Required: Yes
Instructions:
1. Update to kubernetes-nmstate-handler-container-v2.3.0-30 or later. 2. Restart affected containers. 3. Verify the new version is running.
🔧 Temporary Workarounds
Container Security Context Hardening
linuxConfigure containers to run as non-root user and restrict file system permissions
securityContext:
runAsNonRoot: true
runAsUser: 1000
allowPrivilegeEscalation: false
Read-only Root Filesystem
linuxMount container root filesystem as read-only to prevent /etc/passwd modification
securityContext:
readOnlyRootFilesystem: true
🧯 If You Can't Patch
- Implement strict network policies to limit container-to-container communication
- Deploy runtime security monitoring to detect privilege escalation attempts
🔍 How to Verify
Check if Vulnerable:
Check container image version: kubectl get pods -n nmstate -o jsonpath='{.items[*].spec.containers[*].image}' | grep nmstate-handlerCheck Version:
kubectl describe pod <pod-name> -n nmstate | grep ImageVerify Fix Applied:
Verify running version is v2.3.0-30 or later using kubectl describe pod📡 Detection & Monitoring
Log Indicators:
- Unexpected modifications to /etc/passwd in container logs
- Privilege escalation attempts in audit logs
Network Indicators:
- Unusual outbound connections from nmstate containers
- Lateral movement attempts within cluster
SIEM Query:
source="container-logs" AND ("etc/passwd" OR "privilege escalation") AND image="*nmstate-handler*"