CVE-2021-45733 – This vulnerability allows remote attackers to e... (How to Fix)

📋 TL;DR

This vulnerability allows remote attackers to execute arbitrary commands on TOTOLINK X5000R routers by injecting malicious commands into the NTPSyncWithHost function's host_time parameter. Attackers can gain full control of affected devices. Only TOTOLINK X5000R routers running vulnerable firmware versions are affected.

💻 Affected Systems

Products:

TOTOLINK X5000R

Versions: v9.1.0u.6118_B20201102 and likely earlier versions

Operating Systems: Embedded Linux

Default Config Vulnerable: ⚠️ Yes

Notes: All devices running the vulnerable firmware are affected regardless of configuration.

📦 What is this software?

X5000r Firmware by Totolink

View all CVEs affecting X5000r Firmware →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete compromise of router with persistent backdoor installation, credential theft, network pivoting to internal systems, and device bricking.

🟠

Likely Case

Router takeover for botnet recruitment, DNS hijacking, credential harvesting, and network traffic interception.

🟢

If Mitigated

Limited impact if device is behind firewall with restricted WAN access and proper network segmentation.

🌐 Internet-Facing: HIGH - Routers are typically internet-facing devices with direct exposure to attackers.

🏢 Internal Only: MEDIUM - Internal attackers could exploit if they gain network access, but external exposure is primary concern.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploit requires sending crafted HTTP request to vulnerable endpoint. Public proof-of-concept exists in GitHub repository.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Unknown

Vendor Advisory: Not available

Restart Required: Yes

Instructions:

1. Check TOTOLINK website for firmware updates
2. Download latest firmware for X5000R
3. Access router admin interface
4. Navigate to firmware upgrade section
5. Upload and apply new firmware
6. Reboot router

🔧 Temporary Workarounds

Disable NTP synchronization

all

Prevent exploitation by disabling the vulnerable NTP synchronization feature

Network isolation

all

Place router behind firewall with strict inbound rules

🧯 If You Can't Patch

Replace vulnerable router with different model
Implement strict network segmentation to isolate router from critical systems

🔍 How to Verify

Check if Vulnerable:

Check firmware version in router admin interface. If version is v9.1.0u.6118_B20201102 or earlier, device is vulnerable.

Check Version:

Login to router admin interface and check System Status or Firmware Information page

Verify Fix Applied:

Verify firmware version has been updated to a version later than v9.1.0u.6118_B20201102

📡 Detection & Monitoring

Log Indicators:

Unusual NTP synchronization requests
Command execution patterns in system logs
Unexpected process creation

Network Indicators:

HTTP POST requests to NTP-related endpoints with suspicious parameters
Outbound connections from router to unexpected destinations

SIEM Query:

source="router_logs" AND ("NTPSyncWithHost" OR "host_time" AND command_execution_patterns)

📊 Metadata

CVE ID: CVE-2021-45733

CVSS v3 Score: 9.8 (CRITICAL)

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE: CWE-77

Published: February 4, 2022

Last Updated: November 21, 2024

🔗 References

https://github.com/pjqwudi/my_vuln/blob/main/totolink/vuln_7/7.md Exploit,Third Party Advisory
https://github.com/pjqwudi/my_vuln/blob/main/totolink/vuln_7/7.md Exploit,Third Party Advisory

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🔗 Related Vulnerabilities

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