CVE-2021-41426
📋 TL;DR
CVE-2021-41426 is a Cross-Site Request Forgery (CSRF) vulnerability in Beeline Smart Box 2.0.38 routers that allows attackers to trick authenticated users into performing unintended actions via the mgt_end_user.htm endpoint. This affects users of Beeline Smart Box routers who access the web management interface while authenticated. Attackers can exploit this to change router settings without the user's knowledge.
💻 Affected Systems
- Beeline Smart Box
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An attacker could completely compromise the router by changing administrative credentials, DNS settings, firewall rules, or network configuration, leading to man-in-the-middle attacks, network redirection, or complete loss of control.
Likely Case
Attackers could change Wi-Fi passwords, disable security features, or redirect DNS to malicious servers, potentially compromising all devices on the network.
If Mitigated
With proper CSRF protections and network segmentation, impact would be limited to isolated network segments with minimal critical systems exposed.
🎯 Exploit Status
Exploitation requires the victim to be logged into the router's web interface and visit a malicious webpage. Video demonstrations show practical exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown specific version, but vendor has released updates
Vendor Advisory: https://tula.beeline.ru/customers/pomosh/home/domashnij-internet/nastrojki-s-routerom/beelinesmartbox/
Restart Required: Yes
Instructions:
1. Log into Beeline Smart Box web interface
2. Navigate to firmware update section
3. Check for and apply latest firmware update
4. Reboot router after update completes
🔧 Temporary Workarounds
Use separate browser for router admin
allUse a dedicated browser or private/incognito window only for router administration to prevent CSRF attacks from other browsing sessions.
Log out after administration
allAlways log out of the router web interface immediately after making changes to prevent persistent authenticated sessions.
🧯 If You Can't Patch
- Segment router management to isolated VLAN or network segment
- Implement network-level protections like WAF with CSRF rules if router is exposed
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in web interface under System Status or About page. If version is 2.0.38, the device is vulnerable.Check Version:
No CLI command - check via web interface at http://router-ip/status.htm or similarVerify Fix Applied:
After updating, verify firmware version is no longer 2.0.38 and test CSRF protection by attempting to replicate attack vectors shown in proof-of-concept videos.📡 Detection & Monitoring
Log Indicators:
- Multiple configuration changes from same IP in short timeframe
- Unusual parameter values in POST requests to mgt_end_user.htm
Network Indicators:
- HTTP requests to router IP containing CSRF-like payloads
- Traffic patterns showing router admin interface accessed followed by external web requests
SIEM Query:
source="router_logs" AND (uri="/mgt_end_user.htm" OR uri CONTAINS "mgt_end_user") AND method="POST"🔗 References
- https://tula.beeline.ru/customers/pomosh/home/domashnij-internet/nastrojki-s-routerom/beelinesmartbox/
- https://youtu.be/HL73yOW7YWU?t=540
- https://youtu.be/WtcyIVImcwc
- https://tula.beeline.ru/customers/pomosh/home/domashnij-internet/nastrojki-s-routerom/beelinesmartbox/
- https://youtu.be/HL73yOW7YWU?t=540
- https://youtu.be/WtcyIVImcwc
