CVE-2024-32937
📋 TL;DR
This CVE describes an OS command injection vulnerability in Grandstream GXP2135 IP phones' CWMP SelfDefinedTimeZone functionality. Attackers can send specially crafted network packets to execute arbitrary commands on affected devices. Organizations using vulnerable Grandstream GXP2135 phones are at risk.
💻 Affected Systems
- Grandstream GXP2135 IP Phone
📦 What is this software?
Gxp2135 Firmware by Grandstream
Gxp2135 Firmware by Grandstream
Gxp2135 Firmware by Grandstream
⚠️ Risk & Real-World Impact
Worst Case
Full device compromise allowing attacker to install persistent backdoors, pivot to internal networks, intercept communications, or brick devices.
Likely Case
Remote code execution leading to device takeover, credential theft, call interception, or participation in botnets.
If Mitigated
Limited impact if devices are behind firewalls with strict network segmentation and packet filtering.
🎯 Exploit Status
Exploitation requires sending specially crafted CWMP packets to the device's management interface.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Grandstream security advisory for latest patched version
Vendor Advisory: https://www.grandstream.com/support/security-advisories
Restart Required: Yes
Instructions:
1. Download latest firmware from Grandstream support portal. 2. Upload firmware to device via web interface. 3. Apply firmware update. 4. Reboot device.
🔧 Temporary Workarounds
Network Segmentation
allIsolate IP phones on separate VLAN with restricted access to management interfaces
Firewall Rules
allBlock external access to device management ports (typically 80, 443, 5060, 5061)
🧯 If You Can't Patch
- Segment devices on isolated network with strict egress filtering
- Implement network monitoring for unusual CWMP traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check device firmware version via web interface: System Status > System InformationCheck Version:
Web interface navigation or SSH command if enabled: cat /etc/versionVerify Fix Applied:
Verify firmware version is updated beyond affected versions and test with known exploit payloads📡 Detection & Monitoring
Log Indicators:
- Unusual CWMP packet patterns
- Unexpected system command execution in logs
- Failed authentication attempts on management interface
Network Indicators:
- Malformed CWMP packets to port 7547
- Unusual outbound connections from IP phones
- Shell command patterns in network traffic
SIEM Query:
source="firewall" dest_port=7547 AND (payload CONTAINS "|" OR payload CONTAINS ";" OR payload CONTAINS "`")