CVE-2021-30072
📋 TL;DR
This vulnerability allows unauthenticated attackers to execute arbitrary code on D-Link DIR-878 routers via a stack-based buffer overflow in the prog.cgi component. Attackers can potentially take full control of affected devices remotely. All users of DIR-878 routers with firmware version 1.30B08 are affected.
💻 Affected Systems
- D-Link DIR-878
📦 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 network exposure remains.
🎯 Exploit Status
The vulnerability requires no authentication and has a public proof-of-concept available, making exploitation straightforward for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Firmware version 1.30B10 or later
Vendor Advisory: https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10217
Restart Required: Yes
Instructions:
1. Download latest firmware from D-Link support site. 2. Log into router admin interface. 3. Navigate to System > Firmware Update. 4. Upload and install new firmware. 5. Reboot router after installation.
🔧 Temporary Workarounds
Disable remote management
allPrevents external attackers from accessing the vulnerable interface
Network segmentation
allIsolate router management interface from untrusted networks
🧯 If You Can't Patch
- Replace affected device with patched or different model
- Implement strict network access controls to limit exposure to the router's management interface
🔍 How to Verify
Check if Vulnerable:
Check firmware version in router web interface under System > Firmware UpdateCheck Version:
Check router web interface or use nmap to identify firmware versionVerify Fix Applied:
Confirm firmware version is 1.30B10 or later in System > Firmware Update page📡 Detection & Monitoring
Log Indicators:
- Unusual HTTP requests to prog.cgi
- Multiple failed exploit attempts
- Unexpected router reboots
Network Indicators:
- Unusual traffic patterns to router management interface
- Exploit payloads in HTTP requests
SIEM Query:
source_ip="router_ip" AND (uri="*prog.cgi*" OR http_user_agent="*exploit*")