CVE-2024-41585: Draytek Vigor3910 Firmware RCE Vulnerability

CVE-2024-41585 Overview

CVE-2024-41585 is an OS command injection vulnerability affecting DrayTek Vigor3910 devices running firmware through version 4.3.2.6. This vulnerability allows an attacker to leverage the recvCmd binary to escape from the emulated instance and inject arbitrary commands into the host machine. Classified as CWE-78 (Improper Neutralization of Special Elements used in an OS Command), this flaw enables attackers with adjacent network access and high privileges to compromise the underlying host system.

Critical Impact

Successful exploitation allows attackers to escape virtualization boundaries and execute arbitrary commands on the host machine, potentially leading to complete device compromise with high impact to confidentiality, integrity, and availability.

Affected Products

• DrayTek Vigor3910 Firmware (versions through 4.3.2.6)
• DrayTek Vigor3910 Hardware Device

Discovery Timeline

• 2024-10-03 - CVE-2024-41585 published to NVD
• 2025-04-10 - Last updated in NVD database

Technical Details for CVE-2024-41585

Vulnerability Analysis

This OS command injection vulnerability exists within the DrayTek Vigor3910's recvCmd binary component. The vulnerability allows authenticated attackers with adjacent network access to break out of the emulated environment and inject malicious commands that execute on the host operating system. The attack requires high privileges but no user interaction, making it exploitable by authenticated administrators or attackers who have compromised administrative credentials.

The vulnerability's impact is significant because it bypasses the security boundary between the emulated instance and the host machine. Once an attacker successfully exploits this flaw, they gain the ability to execute arbitrary commands with the privileges of the host system, effectively compromising the entire device rather than just the virtualized environment.

Root Cause

The root cause of CVE-2024-41585 is improper neutralization of special elements used in OS commands (CWE-78). The recvCmd binary fails to properly sanitize or validate input before passing it to system command execution functions. This allows specially crafted input containing command separators or shell metacharacters to break out of the intended command context and execute attacker-controlled commands on the host system.

Attack Vector

The attack vector for this vulnerability requires adjacent network access, meaning the attacker must be on the same network segment as the vulnerable device. Additionally, high privileges are required, indicating that the attacker needs administrative or elevated access to the device's management interface. The attack does not require user interaction and operates within an unchanged scope, meaning the vulnerable component and impacted component are the same.

The exploitation mechanism involves sending malicious input to the recvCmd binary that includes OS command injection payloads. These payloads escape the emulated instance's boundary and execute directly on the host machine. Security researchers at Forescout documented this vulnerability as part of their "Draybreak" research initiative covering multiple DrayTek vulnerabilities.

For detailed technical analysis of the exploitation mechanism, refer to the Forescout Research on Draybreak documentation.

Detection Methods for CVE-2024-41585

Indicators of Compromise

• Unexpected processes spawned by the recvCmd binary on DrayTek Vigor3910 devices
• Anomalous outbound network connections originating from the host system rather than the emulated instance
• Unauthorized configuration changes or new user accounts created on the device
• Evidence of command execution artifacts such as reverse shells or reconnaissance tool outputs

Detection Strategies

• Monitor DrayTek device logs for unusual administrative access patterns, particularly from adjacent network segments
• Implement network segmentation monitoring to detect lateral movement attempts from compromised network devices
• Deploy network intrusion detection signatures for known DrayTek command injection patterns
• Audit firmware versions across all DrayTek devices and flag any running versions at or below 4.3.2.6

Monitoring Recommendations

• Enable detailed logging on DrayTek Vigor3910 devices and forward logs to a centralized SIEM solution
• Monitor for unusual process execution patterns on network infrastructure devices
• Implement alerting for any configuration changes made to DrayTek devices outside of scheduled maintenance windows
• Conduct regular vulnerability scans specifically targeting network infrastructure firmware versions

How to Mitigate CVE-2024-41585

Immediate Actions Required

• Update DrayTek Vigor3910 firmware to a version newer than 4.3.2.6 that addresses this vulnerability
• Restrict management interface access to trusted networks and specific administrator IP addresses only
• Review and audit all administrative accounts on affected devices for unauthorized access
• Implement network segmentation to isolate management interfaces from general network traffic

Patch Information

DrayTek has addressed this vulnerability in firmware releases following version 4.3.2.6. Organizations should consult the Forescout DrayTek Vulnerabilities Report for comprehensive information about this and related vulnerabilities. Contact DrayTek support or visit the official DrayTek website to obtain the latest firmware version that remediates CVE-2024-41585.

Workarounds

• Restrict administrative access to the device from trusted IP addresses only using access control lists (ACLs)
• Disable remote management interfaces if not required for operational needs
• Place DrayTek devices behind a firewall that limits adjacent network access to authorized systems
• Implement strong authentication and multi-factor authentication where supported for administrative access
• Monitor and log all administrative sessions for forensic purposes

# Example ACL configuration to restrict management access
# Consult DrayTek documentation for device-specific syntax
# Limit management interface access to specific admin subnet
# Enable logging for all administrative access attempts
# Disable unused remote management protocols