CVE-2021-29998
📋 TL;DR
CVE-2021-29998 is a heap overflow vulnerability in the DHCP client of Wind River VxWorks operating system. This allows remote attackers to execute arbitrary code or cause denial of service by sending specially crafted DHCP packets. Systems running VxWorks versions before 6.5 with DHCP client enabled are affected.
💻 Affected Systems
- Wind River VxWorks
📦 What is this software?
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Vxworks by Windriver
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, allowing attackers to take control of affected devices.
Likely Case
Denial of service causing system crashes or instability, potentially disrupting critical operations.
If Mitigated
Limited impact if network segmentation prevents external DHCP traffic from reaching vulnerable systems.
🎯 Exploit Status
Exploitation requires sending malicious DHCP packets to vulnerable systems. No authentication needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: VxWorks 6.5 and later
Vendor Advisory: https://support2.windriver.com/index.php?page=security-notices
Restart Required: Yes
Instructions:
1. Contact Wind River for patches for specific VxWorks versions. 2. Apply the provided patches. 3. Reboot affected systems. 4. Verify patch installation.
🔧 Temporary Workarounds
Disable DHCP Client
allConfigure systems to use static IP addresses instead of DHCP
# Configure static IP in VxWorks network settings
# Set IP address, netmask, gateway manually
Network Segmentation
allIsolate VxWorks systems from untrusted networks
# Configure firewall rules to block DHCP traffic (ports 67/68) from untrusted sources
🧯 If You Can't Patch
- Implement strict network segmentation to isolate VxWorks systems
- Deploy network intrusion detection systems to monitor for DHCP exploitation attempts
🔍 How to Verify
Check if Vulnerable:
Check VxWorks version and verify if DHCP client is enabled. Versions before 6.5 are vulnerable.Check Version:
versionShow() or uname -a in VxWorks shellVerify Fix Applied:
Verify system is running VxWorks 6.5 or later, or confirm patch installation from vendor.📡 Detection & Monitoring
Log Indicators:
- DHCP client crashes
- Memory corruption errors
- System reboots without clear cause
Network Indicators:
- Unusual DHCP traffic patterns
- DHCP packets with malformed options
SIEM Query:
search DHCP traffic with suspicious option fields or from untrusted sources🔗 References
- https://cert-portal.siemens.com/productcert/pdf/ssa-560465.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-910883.pdf
- https://support2.windriver.com/index.php?page=security-notices
- https://us-cert.cisa.gov/ics/advisories/icsa-21-194-12
- https://cert-portal.siemens.com/productcert/pdf/ssa-560465.pdf
- https://cert-portal.siemens.com/productcert/pdf/ssa-910883.pdf
- https://support2.windriver.com/index.php?page=security-notices
- https://us-cert.cisa.gov/ics/advisories/icsa-21-194-12
