CVE-2025-31702

Executive Summary

CVE-2025-31702 is a privilege escalation vulnerability in certain Dahua embedded products. A third-party malicious attacker who has obtained normal user credentials can exploit this flaw to access data normally restricted to admin privileges, including system-sensitive files, via a crafted HTTP request. This can lead to tampering with the admin password and subsequent privilege escalation. Systems configured with only an admin account are not affected. The vulnerability has a CVSS score of 6.8 (Medium), and no public proof-of-concept or patch details are currently available.

CVSS Breakdown & Threat Level

• CVSS Score: 6.8 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – requires normal user credentials
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: High (C:H)
• Integrity Impact: High (I:H)
• Availability Impact: None (A:N)

The threat level is elevated due to the low complexity and network-based attack vector, combined with high impact on confidentiality and integrity. The requirement for valid user credentials reduces the immediate risk but still poses a significant threat in multi-user environments.

Deep Dive & Mechanics

The vulnerability resides in the HTTP request handling of Dahua embedded products. When a normal user sends a specially crafted HTTP request, the server incorrectly processes the request and grants access to endpoints or files that should be restricted to admin privileges. This includes system-sensitive files that can be used to extract or modify the admin password hash.

The root cause is likely improper authorization checks in the web server or API layer. The server fails to validate that the requesting user has the required admin role before serving sensitive data or performing privileged actions. By manipulating request parameters, headers, or paths, an attacker can bypass the intended access controls.

Vulnerable vs. Patched Code

No specific code snippets are available. However, the vulnerable code likely resembles:

# Vulnerable pseudo-code
@app.route('/admin/sensitive')
def get_sensitive_data():
    user = get_current_user()
    # Missing role check
    return read_sensitive_file()

A patched version would include proper authorization:

# Patched pseudo-code
@app.route('/admin/sensitive')
def get_sensitive_data():
    user = get_current_user()
    if user.role != 'admin':
        abort(403)
    return read_sensitive_file()

Exploitation & Lab Setup

Red Team

Prerequisites:

• Valid normal user credentials for a Dahua embedded product.
• Network access to the target device.

Exploitation Steps:

1. Authenticate to the device using the normal user credentials.
2. Identify the vulnerable endpoint (e.g., /cgi-bin/exportSettings, /config/backup).
3. Craft an HTTP request that bypasses role checks, such as adding an X-Forwarded-For: admin header or manipulating a role parameter.
4. Send the request and retrieve system-sensitive files (e.g., /etc/shadow, admin password hash).
5. Crack the admin password hash offline.
6. Use the admin credentials to gain full control.

Example Request:

POST /cgi-bin/exportSettings HTTP/1.1
Host: target-device
Authorization: Basic <base64(normal_user:password)>
X-Forwarded-For: admin
Content-Type: application/x-www-form-urlencoded

action=export&type=admin

Blue Team

Detection:

• Monitor for unusual HTTP requests from normal user accounts to admin-only endpoints.
• Alert on requests containing headers like X-Forwarded-For: admin or parameters like role=admin.
• Track failed authentication attempts followed by successful access to sensitive files.

Prevention:

• Implement strict role-based access control (RBAC) on all endpoints.
• Validate user roles server-side, not relying on client-supplied data.
• Use Web Application Firewall (WAF) rules to block known bypass patterns.
• Regularly audit user accounts and remove unused normal users.

Indicators of Compromise (IOCs)

• Network: HTTP requests to /cgi-bin/exportSettings, /config/backup, or similar admin endpoints from non-admin users.
• Logs: Access logs showing normal user accounts accessing files like /etc/shadow or /admin/config.
• File: Presence of exported configuration files containing admin password hashes on unauthorized systems.
• Behavior: Multiple failed login attempts followed by successful access to sensitive endpoints.

Detection Engineering

YARA Rule

rule CVE_2025_31702_Dahua_PrivEsc {
    meta:
        description = "Detects HTTP requests attempting to exploit CVE-2025-31702"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-31702"
    strings:
        $s1 = "X-Forwarded-For: admin" ascii nocase
        $s2 = "role=admin" ascii nocase
        $s3 = "/cgi-bin/exportSettings" ascii nocase
        $s4 = "/config/backup" ascii nocase
    condition:
        any of ($s1, $s2) and any of ($s3, $s4)
}

Sigma Rule

title: CVE-2025-31702 Dahua Privilege Escalation Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests from normal users to admin-only endpoints on Dahua devices
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: dahua
detection:
    selection:
        http.method: 'POST'
        http.url|contains:
            - '/cgi-bin/exportSettings'
            - '/config/backup'
        http.user_agent|contains: 'Mozilla'
    condition: selection
falsepositives:
    - Legitimate admin activity from admin accounts
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-31702 Dahua Privilege Escalation Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/cgi-bin/exportSettings"; http_uri;
    content:"X-Forwarded-For: admin"; http_header;
    sid:1000001;
    rev:1;
    reference:cve,2025-31702;
    classtype:attempted-admin;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Restrict network access to Dahua devices to trusted IPs only.
2. Disable or remove all non-admin user accounts if not required.
3. Monitor logs for suspicious access patterns.

Long-term Fix:

• Apply vendor patch when available.
• Implement network segmentation to isolate embedded devices.
• Use strong, unique passwords for all accounts.
• Enable multi-factor authentication if supported.

Workarounds:

• Configure the device to only allow admin accounts (if feasible).
• Use a reverse proxy with additional authentication and authorization checks.

Valters IT