CVE-2023-35193
📋 TL;DR
This CVE describes an OS command injection vulnerability in Peplink Surf SOHO HW1 routers that allows authenticated attackers to execute arbitrary commands via a crafted HTTP request to the api.cgi endpoint. The vulnerability affects firmware version 6.3.5 and enables remote code execution on the device. Attackers with valid credentials can exploit this to gain control of affected routers.
💻 Affected Systems
- Peplink Surf SOHO HW1
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router leading to network infiltration, data exfiltration, lateral movement to connected devices, and persistent backdoor installation.
Likely Case
Attacker gains shell access to router, modifies configurations, intercepts network traffic, and potentially uses router as pivot point for further attacks.
If Mitigated
Limited impact due to network segmentation, strong authentication controls, and restricted administrative access.
🎯 Exploit Status
Exploitation requires valid credentials but is straightforward once authenticated. The specific offset (0x4bddb8) and system call location are documented.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Peplink security advisories for patched version
Vendor Advisory: https://www.peplink.com/security/
Restart Required: Yes
Instructions:
1. Check current firmware version. 2. Download latest firmware from Peplink support portal. 3. Upload firmware via web interface. 4. Apply update and restart device.
🔧 Temporary Workarounds
Restrict Administrative Access
allLimit access to the web interface to trusted IP addresses only
Configure firewall rules to restrict access to router management interface
Disable Unnecessary Services
allDisable remote management features if not required
Disable WAN-side administrative access in router settings
🧯 If You Can't Patch
- Implement network segmentation to isolate affected routers from critical systems
- Enforce strong authentication policies and monitor for suspicious login attempts
🔍 How to Verify
Check if Vulnerable:
Check firmware version via web interface: System > Firmware. If version is 6.3.5, device is vulnerable.Check Version:
Check via web interface or SSH if enabled: cat /etc/versionVerify Fix Applied:
Verify firmware version has been updated to a version later than 6.3.5📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP POST requests to /web/MANGA/cgi-bin/api.cgi
- Suspicious command execution in system logs
- Multiple failed authentication attempts followed by successful login
Network Indicators:
- Unusual outbound connections from router
- Traffic patterns suggesting command and control communication
SIEM Query:
source="router_logs" AND (uri="/web/MANGA/cgi-bin/api.cgi" OR cmd="system")