CVE-2024-25657

Executive Summary

CVE-2024-25657 is an open redirect vulnerability in the Login/Logout functionality of the AVSystem Unified Management Platform (UMP) version 23.07.0.16567~LTS. This flaw allows an attacker to redirect authenticated users to malicious external websites, enabling phishing attacks, credential theft, or malware distribution. The vulnerability is classified as CWE-601 (URL Redirection to Untrusted Site) and has a CVSS v3.1 base score of 4.7 (Medium). No public exploit code or patch is currently available, and the vendor has not released a fix. The EPSS score is 0.0%, indicating low exploitation likelihood at this time, but the risk remains for targeted attacks.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary Java-based web management platform (AVSystem UMP) used in IoT and telecom environments. No open-source package dependencies are involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 4.7 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed to trigger the redirect.
• User Interaction: Required (UI:R) – Victim must click a crafted link.
• Scope: Changed (S:C) – Redirect leads to an external domain.
• Confidentiality Impact: Low (C:L) – Potential exposure of session tokens or credentials.
• Integrity Impact: Low (I:L) – Redirected content may be manipulated.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. While the CVSS score is moderate, the lack of a patch and the potential for phishing campaigns targeting authenticated users elevates the risk in enterprise deployments.

Deep Dive & Mechanics

The vulnerability resides in the Login/Logout functionality of AVSystem UMP. When a user logs in or out, the application may accept a redirect parameter (or similar) in the URL to return the user to a specific page after authentication. Due to insufficient validation, an attacker can craft a URL like:

https://ump.example.com/login?redirect=https://malicious-site.com

If an authenticated user clicks this link (e.g., via a phishing email), the application will redirect them to the attacker-controlled site after the login/logout action. This can be used to steal session cookies, credentials, or deliver malware.

The vulnerability is likely in the server-side code that handles the redirect parameter. The application fails to validate that the redirect URL belongs to a whitelisted domain or uses a relative path.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common open redirect fixes.

Vulnerable Code (Java/Spring example):

@GetMapping("/login")
public String login(@RequestParam(value = "redirect", required = false) String redirect) {
    if (redirect != null) {
        return "redirect:" + redirect;
    }
    return "login";
}

Patched Code (with whitelist validation):

@GetMapping("/login")
public String login(@RequestParam(value = "redirect", required = false) String redirect) {
    if (redirect != null && isValidRedirect(redirect)) {
        return "redirect:" + redirect;
    }
    return "login";
}

private boolean isValidRedirect(String url) {
    try {
        URI uri = new URI(url);
        String host = uri.getHost();
        return host != null && host.endsWith(".example.com");
    } catch (URISyntaxException e) {
        return false;
    }
}

The patched version validates the redirect URL against a whitelist of allowed domains (e.g., *.example.com). Without this, any external URL is accepted.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Access to a vulnerable AVSystem UMP instance (version 23.07.0.16567~LTS).
• A publicly accessible malicious website (e.g., http://attacker.com).

Exploitation Steps:

1. Craft a phishing URL:

   https://ump.victim.com/login?redirect=http://attacker.com/fake-login
   

2. Send the link to an authenticated user via email or social engineering.
3. When the user clicks the link, they are redirected to the attacker's site after login/logout.
4. On the attacker's site, clone the UMP login page to capture credentials or session tokens.

Example Payload:

<a href="https://ump.victim.com/logout?redirect=https://attacker.com/steal">Click here to log out</a>

Blue Team (Detection & Defense)

Detection:

• Monitor web logs for unusual redirect parameters pointing to external domains.
• Alert on multiple failed login attempts followed by redirects to unknown hosts.
• Use the YARA and Sigma rules below to detect exploitation attempts.

Defense:

• Implement a web application firewall (WAF) rule to block redirects to external domains.
• Enforce strict validation of the redirect parameter on the server side.
• Educate users about phishing attacks involving open redirects.

Indicators of Compromise (IOCs)

• URL Patterns:
  • /login?redirect=http:// or https:// (external domain)
  • /logout?redirect=http:// or https:// (external domain)
• Network Traffic:
  • HTTP requests to the UMP server with redirect parameter containing non-whitelisted domains.
  • Subsequent connections to external domains shortly after UMP login/logout.
• Log Entries:
  • Web server logs showing 302 redirect responses with external URLs in the Location header.

Detection Engineering

YARA Rule

rule CVE_2024_25657_Open_Redirect {
    meta:
        description = "Detects open redirect attempts in AVSystem UMP login/logout URLs"
        author = "Valters IT"
        date = "2025-04-14"
        cve = "CVE-2024-25657"
    strings:
        $redirect_param = /[?&]redirect=(http|https):\/\// nocase
        $ump_path = /\/login|\/logout/ nocase
    condition:
        $redirect_param and $ump_path
}

Sigma Rule

title: AVSystem UMP Open Redirect Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP requests to AVSystem UMP with external redirect parameters
author: Valters IT
date: 2025-04-14
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: 
            - "redirect=http://"
            - "redirect=https://"
        cs-uri-stem|contains: 
            - "/login"
            - "/logout"
    condition: selection
falsepositives:
    - Legitimate redirects to internal resources (if misconfigured)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-25657 AVSystem UMP Open Redirect Attempt";
    flow:to_server,established;
    content:"/login"; http_uri; nocase;
    content:"redirect="; http_uri; nocase;
    pcre:"/redirect=(http|https):\/\//Ui";
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the redirect functionality if not required, by modifying the application configuration or using a WAF to block external redirects.
2. Apply a virtual patch using a WAF rule that validates the redirect parameter against a whitelist of allowed domains.
3. Monitor logs for exploitation attempts and block malicious IPs.

Long-Term Fix:

• The vendor (AVSystem) must release a patch that implements proper URL validation (whitelist-based or relative path only).
• Upgrade to a patched version once available.
• Conduct a security review of all redirect mechanisms in the application.

Workaround:

• If source code access is available, modify the login/logout handler to only allow relative redirects (e.g., /dashboard instead of https://external.com).

Valters IT