CVE-2024-7907: Totolink X6000r Firmware RCE Vulnerability

CVE-2024-7907 Overview

CVE-2024-7907 is a command injection vulnerability in the TOTOLINK X6000R router running firmware version 9.4.0cu.852_20230719. The flaw resides in the setSyslogCfg function of /cgi-bin/cstecgi.cgi, where the rtLogServer argument is passed to a shell context without sanitization. An authenticated remote attacker can manipulate this parameter to inject arbitrary operating system commands. A public proof-of-concept has been disclosed on GitHub. The vendor was contacted prior to disclosure but did not respond, leaving the affected firmware without an official patch.

Critical Impact

Remote command execution on affected TOTOLINK X6000R devices can give attackers full control of the router, enabling traffic interception, lateral movement, and persistent footholds in the network.

Affected Products

• TOTOLINK X6000R router (hardware)
• TOTOLINK X6000R firmware version 9.4.0cu.852_20230719
• /cgi-bin/cstecgi.cgi CGI handler implementing setSyslogCfg

Discovery Timeline

• 2024-08-18 - CVE-2024-7907 published to NVD with public proof-of-concept referenced via GitHub PoC for Syslog Injection
• 2024-08-19 - Last updated in NVD database

Technical Details for CVE-2024-7907

Vulnerability Analysis

The vulnerability is classified under [CWE-77] Improper Neutralization of Special Elements used in a Command. The setSyslogCfg handler in /cgi-bin/cstecgi.cgi accepts the rtLogServer parameter, which is intended to store the remote syslog server address. Instead of validating or escaping the value, the handler concatenates it into a shell command executed on the underlying Linux system.

An attacker with low-privilege access to the web interface can inject shell metacharacters such as ;, |, or backticks within rtLogServer. The injected payload runs in the context of the CGI process, which on consumer routers typically executes as root. The published EPSS score of 2.036% (84.04 percentile) indicates above-average exploitation likelihood for this class of issue.

Root Cause

The root cause is the absence of input validation and output escaping before passing user-controlled data to a command interpreter. The rtLogServer value flows directly from the HTTP request into a system()-style call, violating the principle of separating data from code.

Attack Vector

The attack is delivered over the network through an HTTP POST request to /cgi-bin/cstecgi.cgi invoking the setSyslogCfg topic name. Because the request requires authentication, attackers commonly chain this issue with default credentials, credential reuse, or earlier authentication bypass flaws in TOTOLINK firmware. Public PoC content describing the payload structure is available in the BeaCox IoT_vuln repository.

// No verified exploit code is reproduced here.
// Refer to the linked PoC repository for technical payload details.

Detection Methods for CVE-2024-7907

Indicators of Compromise

• HTTP POST requests to /cgi-bin/cstecgi.cgi containing the topicurl=setSyslogCfg parameter combined with shell metacharacters in rtLogServer
• Unexpected outbound connections from the router to attacker infrastructure following syslog configuration changes
• New or modified iptables rules, cron entries, or /tmp binaries on the device

Detection Strategies

• Inspect router web traffic for rtLogServer values containing ;, &&, |, backticks, or $() sequences
• Correlate administrative logins followed by syslog configuration changes with anomalous DNS or outbound TCP activity
• Monitor SOHO network segments for routers initiating connections to non-syslog destinations on non-syslog ports

Monitoring Recommendations

• Forward router syslog and authentication events to a centralized log platform for retention and correlation
• Baseline normal management traffic patterns and alert on deviations such as unusual user-agents or off-hours access
• Track firmware version inventory across network devices to identify hosts still running 9.4.0cu.852_20230719

How to Mitigate CVE-2024-7907

Immediate Actions Required

• Restrict access to the router web management interface to trusted management VLANs only
• Rotate administrative credentials and disable remote WAN-side administration
• Audit current rtLogServer values and any syslog configuration for tampering
• Segment SOHO routers away from sensitive internal assets to limit blast radius if a device is compromised

Patch Information

No vendor patch is available. The reporter notes that TOTOLINK was contacted prior to disclosure and did not respond. Track the VulDB entry #275033 for future firmware updates and consider replacing the device if a fix is not released within an acceptable timeframe.

Workarounds

• Disable remote syslog configuration in the web UI if the feature is not required
• Place the router behind an upstream firewall that filters management plane access
• Replace affected X6000R units with devices that receive active security maintenance when feasible

# Example: block external access to the router management interface
iptables -A INPUT -p tcp --dport 80 ! -s 192.0.2.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 ! -s 192.0.2.0/24 -j DROP