CVE-2023-20125
📋 TL;DR
This vulnerability allows an unauthenticated remote attacker to send a high rate of TCP connections to the Cisco BroadWorks Network Server, exhausting system resources and causing a denial of service (DoS). It affects systems running vulnerable versions of Cisco BroadWorks Network Server software, potentially rendering them unusable until restarted.
💻 Affected Systems
- Cisco BroadWorks Network Server
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete unavailability of the Cisco BroadWorks Network Server, disrupting telephony and communication services until the server is restarted or rebooted.
Likely Case
Degraded performance or temporary service outages due to resource exhaustion, requiring manual intervention to restore functionality.
If Mitigated
Minimal impact if patched or if network controls block unauthorized TCP connections, but risk remains if unpatched and exposed.
🎯 Exploit Status
Exploitation involves sending a high rate of TCP connections, which is straightforward and does not require authentication, increasing the likelihood of attacks.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Refer to Cisco Security Advisory for specific patched versions.
Vendor Advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bw-tcp-dos-KEdJCxLs
Restart Required: Yes
Instructions:
1. Review the Cisco Security Advisory for affected versions. 2. Download and apply the recommended software update from Cisco. 3. Restart the Cisco BroadWorks Network Server to implement the patch.
🔧 Temporary Workarounds
No workarounds available
allCisco states there are no workarounds that address this vulnerability; patching is the only solution.
🧯 If You Can't Patch
- Implement network-level rate limiting or firewall rules to restrict TCP connections to the server from untrusted sources.
- Monitor system resources and logs for signs of DoS attacks, and have an incident response plan ready to restart the server if exploited.
🔍 How to Verify
Check if Vulnerable:
Check the Cisco BroadWorks Network Server version against the affected versions listed in the Cisco Security Advisory.Check Version:
Use Cisco BroadWorks administrative tools or CLI commands specific to the deployment; consult Cisco documentation for exact commands.Verify Fix Applied:
After patching, verify the server version matches the patched version from the advisory and monitor for abnormal TCP connection rates.📡 Detection & Monitoring
Log Indicators:
- Unusually high number of TCP connection attempts in server logs
- Resource exhaustion alerts (e.g., memory or connection limits)
Network Indicators:
- Spike in incoming TCP connections to the server's local interface
- Network traffic patterns indicative of DoS attacks
SIEM Query:
Example: search for events where source IPs generate excessive TCP SYN packets to the Cisco BroadWorks server port over a short time window.