CVE-2020-13601
📋 TL;DR
This vulnerability in Zephyr RTOS allows attackers to read memory beyond allocated bounds during DNS processing, potentially exposing sensitive data or causing crashes. It affects Zephyr versions >=1.14.2 and >=2.3.0 when DNS functionality is enabled.
💻 Affected Systems
- Zephyr RTOS
📦 What is this software?
Zephyr by Zephyrproject
Zephyr by Zephyrproject
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data exfiltration, or persistent backdoor installation.
Likely Case
Denial of service through system crashes or information disclosure of adjacent memory contents.
If Mitigated
Limited impact with proper network segmentation and minimal DNS exposure.
🎯 Exploit Status
Exploitation requires network access to DNS services and specific malformed DNS packets.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in versions after the affected ranges; check specific Zephyr releases.
Vendor Advisory: https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-mm57-9hqw-qh44
Restart Required: Yes
Instructions:
1. Update Zephyr to a patched version. 2. Rebuild and redeploy the firmware. 3. Restart affected devices.
🔧 Temporary Workarounds
Disable DNS functionality
allRemove DNS support from the build configuration if not required.
CONFIG_DNS_RESOLVER=n in prj.conf or Kconfig
Network filtering
allBlock external DNS queries at network boundaries.
🧯 If You Can't Patch
- Segment affected devices on isolated networks with strict firewall rules.
- Implement intrusion detection to monitor for anomalous DNS traffic patterns.
🔍 How to Verify
Check if Vulnerable:
Check Zephyr version and verify DNS functionality is enabled in build configuration.Check Version:
Check Zephyr version in source code or build output.Verify Fix Applied:
Confirm Zephyr version is updated beyond affected ranges and rebuild with latest source.📡 Detection & Monitoring
Log Indicators:
- System crashes during DNS operations
- Memory access violation logs
Network Indicators:
- Malformed DNS packets to Zephyr devices
- Unusual DNS query patterns
SIEM Query:
dns AND (zephyr OR iot_device) AND (malformed OR crash)