CVE-2025-15258

Executive Summary

CVE-2025-15258 identifies an open redirect vulnerability in the Edimax BR-6208AC V2 router, specifically in firmware versions 1.02 and 1.03. The flaw resides in the formALGSetup function within the /goform/formALGSetup endpoint of the web-based configuration interface. By manipulating the wlan-url argument, an unauthenticated remote attacker can redirect a user to an arbitrary external domain. This is a classic open redirect (CWE-601) with a low CVSS score of 3.5, but it can be leveraged for phishing campaigns or as a stepping stone in more complex attacks. The device has reached End of Life (EOL) and will receive no patches, making all deployed units permanently vulnerable.

Supply Chain & Package Security

This vulnerability is not related to any software package registry (NPM, PyPI, Go, Ruby). It affects a hardware appliance (Edimax BR-6208AC V2 router) and its embedded firmware. No supply chain package security implications apply.

CVSS Breakdown & Threat Level

• CVSS Score: 3.5 (Low)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
• Attack Vector (AV): Network – exploitable remotely.
• Attack Complexity (AC): Low – no special conditions required.
• Privileges Required (PR): None – no authentication needed.
• User Interaction (UI): Required – the victim must click a crafted link.
• Scope (S): Unchanged – the redirect does not affect other components.
• Confidentiality (C): None – no data exposure.
• Integrity (I): Low – the redirect can lead to a malicious site.
• Availability (A): None – no denial of service.

Threat Level: Low. The open redirect requires user interaction and does not directly compromise the router. However, it can be weaponized for social engineering attacks.

Deep Dive & Mechanics

The vulnerability is triggered via an HTTP GET or POST request to /goform/formALGSetup with a crafted wlan-url parameter. The router’s web server does not validate or sanitize the URL, allowing an attacker to specify any external domain. When a legitimate user visits a crafted link (e.g., http://<router-ip>/goform/formALGSetup?wlan-url=http://evil.com), the router responds with an HTTP redirect to the attacker-controlled site.

Root Cause: The formALGSetup function directly uses the wlan-url parameter in a Location header without validation. This is a classic open redirect pattern.

Attack Scenario:

1. Attacker identifies a vulnerable Edimax BR-6208AC router (e.g., via Shodan).
2. Attacker crafts a phishing link: http://<router-ip>/goform/formALGSetup?wlan-url=http://phishing-site.com.
3. Victim clicks the link, is redirected to the phishing site, and may disclose credentials.

Vulnerable vs. Patched Code

No patched version exists. The device is EOL. Below is a conceptual comparison.

Vulnerable Code (pseudo):

def formALGSetup(request):
    wlan_url = request.GET.get('wlan-url')
    # No validation
    return redirect(wlan_url)

Patched Code (hypothetical):

def formALGSetup(request):
    wlan_url = request.GET.get('wlan-url')
    # Validate against allowed domains
    if not is_allowed_domain(wlan_url):
        return error("Invalid URL")
    return redirect(wlan_url)

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A vulnerable Edimax BR-6208AC router (firmware 1.02 or 1.03).
• Network access to the router’s web interface (port 80/443).

Exploit Steps:

1. Identify the router IP (e.g., via Shodan or local network scan).
2. Craft a malicious URL:

   http://<router-ip>/goform/formALGSetup?wlan-url=http://attacker-controlled-site.com
   

3. Send the link to the victim (e.g., via email or social media).
4. Victim clicks the link and is redirected to the attacker’s site.

Proof-of-Concept (PoC) using curl:

curl -v "http://192.168.1.1/goform/formALGSetup?wlan-url=http://evil.com"

Expected response: HTTP 302 with Location: http://evil.com.

Blue Team (Defender)

Detection:

• Monitor HTTP requests to /goform/formALGSetup with suspicious wlan-url parameters.
• Look for redirect responses (HTTP 302) to external domains from the router.

Mitigation:

• Since no patch exists, the only mitigation is to replace the device with a supported model.
• If replacement is not immediate, restrict access to the router’s web interface to trusted IPs only (e.g., via firewall rules).
• Disable remote management if not required.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP request to /goform/formALGSetup with a wlan-url parameter pointing to an external domain.
  • HTTP 302 response from the router with a Location header containing an external URL.
• Host IOCs:
  • Router firmware version 1.02 or 1.03 (check via web interface).
  • Unusual outbound connections from the router to unknown domains (though the redirect is client-side, the router itself does not initiate connections).

Detection Engineering

YARA Rule

rule CVE_2025_15258_Open_Redirect {
    meta:
        description = "Detects open redirect attempts against Edimax BR-6208AC"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2025-15258"
    strings:
        $endpoint = "/goform/formALGSetup"
        $param = "wlan-url="
        $http = "HTTP/1.1"
    condition:
        $endpoint and $param and $http
}

Sigma Rule

title: CVE-2025-15258 Open Redirect on Edimax BR-6208AC
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects HTTP requests to /goform/formALGSetup with a wlan-url parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "/goform/formALGSetup?wlan-url="
    condition: selection
falsepositives:
    - Legitimate administrative use (rare)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-15258 Edimax BR-6208AC Open Redirect"; flow:to_server; content:"/goform/formALGSetup"; http_uri; content:"wlan-url="; http_uri; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Replace the device: The Edimax BR-6208AC V2 is EOL and will not receive patches. Upgrade to a supported router model.
2. Restrict access: If replacement is delayed, configure firewall rules to allow only trusted IPs to access the router’s web interface.
3. Disable remote management: Turn off remote administration if not absolutely necessary.

Long-Term Recommendations:

• Conduct a hardware lifecycle review to identify and replace all EOL devices.
• Implement network segmentation to isolate legacy devices.
• Use web application firewalls (WAF) to filter malicious requests if the router is behind a corporate network.

Vendor Statement: Edimax has confirmed the EOL status and recommends upgrading to newer models.

Valters IT