CVE-2021-46315
📋 TL;DR
This CVE describes a remote command execution vulnerability in D-Link DIR-846 routers where attackers can inject shell commands through SSID parameters. The vulnerability affects routers running specific firmware versions and allows unauthenticated attackers to execute arbitrary commands on the device. This is a critical vulnerability due to its high CVSS score and potential for complete device compromise.
💻 Affected Systems
- D-Link DIR-846 Router
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete router takeover allowing attackers to intercept all network traffic, install persistent malware, pivot to internal networks, and use the router as part of a botnet.
Likely Case
Router compromise leading to credential theft, DNS hijacking, man-in-the-middle attacks, and network disruption.
If Mitigated
Limited impact with proper network segmentation and monitoring, though router functionality could still be disrupted.
🎯 Exploit Status
Exploit uses shell metacharacters (backticks, spaces with backslashes) in ssid0/ssid1 parameters. Public PoC available on GitHub.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check D-Link security bulletin for latest patched firmware
Vendor Advisory: https://www.dlink.com/en/security-bulletin/
Restart Required: Yes
Instructions:
1. Visit D-Link support website 2. Download latest firmware for DIR-846 3. Log into router admin interface 4. Navigate to firmware update section 5. Upload and apply new firmware 6. Reboot router
🔧 Temporary Workarounds
Disable HNAP1 Service
allDisable the vulnerable HNAP1 service if not required
Check router admin interface for service disable options
Network Segmentation
allIsolate router management interface from untrusted networks
Configure firewall rules to restrict access to router admin interface
🧯 If You Can't Patch
- Replace affected routers with updated models or different vendors
- Implement strict network monitoring and intrusion detection for router traffic
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface against affected versions. Test if HNAP1/control/SetWizardConfig.php endpoint accepts shell metacharacters.Check Version:
Check router web interface or use: curl -s http://router-ip/status.html | grep firmwareVerify Fix Applied:
Verify firmware version is updated beyond affected versions. Test that shell metacharacters in ssid parameters no longer execute commands.📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to /HNAP1/control/SetWizardConfig.php
- Shell metacharacters in SSID parameters
- Unexpected command execution in router logs
Network Indicators:
- Unusual outbound connections from router
- DNS changes from router
- Traffic redirection patterns
SIEM Query:
source="router-logs" AND (uri="/HNAP1/control/SetWizardConfig.php" AND (ssid0 CONTAINS "`" OR ssid1 CONTAINS "`" OR ssid0 CONTAINS "\\ "))