CVE-2024-2891
📋 TL;DR
This critical vulnerability in Tenda AC7 routers allows remote attackers to execute arbitrary code via a stack-based buffer overflow in the PPPOE password handling function. Attackers can exploit this without authentication to potentially take full control of affected devices. All users running the vulnerable firmware version are at risk.
💻 Affected Systems
- Tenda AC7
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device compromise leading to persistent backdoor installation, network traffic interception, lateral movement to other devices, and botnet recruitment.
Likely Case
Remote code execution allowing attackers to modify router settings, intercept traffic, or use the device as a pivot point for further attacks.
If Mitigated
Limited impact if device is behind firewall with restricted WAN access, though internal attacks remain possible.
🎯 Exploit Status
Public exploit code exists on GitHub, making exploitation trivial for attackers. The vendor has not responded to disclosure.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: None available
Restart Required: Yes
Instructions:
No official patch available. Monitor Tenda website for firmware updates. If update becomes available: 1. Download from official Tenda site 2. Log into router admin 3. Navigate to firmware upgrade section 4. Upload new firmware 5. Wait for reboot
🔧 Temporary Workarounds
Disable WAN Management
allPrevent remote exploitation by disabling router management from WAN/Internet interface
Login to router admin → Advanced Settings → System Tools → Remote Management → Disable
Network Segmentation
allIsolate router management interface to trusted network segment only
🧯 If You Can't Patch
- Replace affected Tenda AC7 routers with different models or brands that are not vulnerable
- Place router behind a firewall that blocks all inbound traffic to router management ports (typically 80, 443, 8080)
🔍 How to Verify
Check if Vulnerable:
1. Access router admin interface 2. Check firmware version in System Status or About page 3. If version is exactly 15.03.06.44, device is vulnerableCheck Version:
curl -s http://router-ip/ | grep -i firmware || Check web interface manuallyVerify Fix Applied:
Check firmware version after any update. Only versions different from 15.03.06.44 might be safe, but verify with vendor.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /goform/QuickIndex
- Multiple failed login attempts followed by buffer overflow patterns
- Router reboot events without user action
Network Indicators:
- Unusual outbound connections from router
- Traffic to known exploit hosting domains
- Port scanning originating from router
SIEM Query:
source="router_logs" AND (uri="/goform/QuickIndex" OR "PPPOEPassword" AND content_length>100)🔗 References
- https://github.com/abcdefg-png/IoT-vulnerable/blob/main/Tenda/AC7/v1/formQuickIndex.md
- https://vuldb.com/?ctiid.257934
- https://vuldb.com/?id.257934
- https://vuldb.com/?submit.300354
- https://github.com/abcdefg-png/IoT-vulnerable/blob/main/Tenda/AC7/v1/formQuickIndex.md
- https://vuldb.com/?ctiid.257934
- https://vuldb.com/?id.257934
- https://vuldb.com/?submit.300354
