CVE-2025-32372

Executive Summary

CVE-2025-32372 is a Server-Side Request Forgery (SSRF) vulnerability in DNN (formerly DotNetNuke), an open-source web content management platform for the Microsoft ecosystem. This vulnerability is a bypass of the previously known CVE-2017-0929, allowing unauthenticated attackers to execute arbitrary GET requests against target systems, including internal or adjacent networks. The attack is semi-blind, meaning the attacker can make the server send requests but cannot view the full responses. Potential impacts include internal network reconnaissance and bypassing firewalls. The vulnerability is fixed in version 9.13.8.

Supply Chain & Package Security

This vulnerability affects the DNN platform, which is distributed as a NuGet package and as a standalone web application. Organizations using DNN should verify their version and update to 9.13.8 or later. The supply chain risk is moderate, as the vulnerability is in the core platform and not in a third-party dependency.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L)
• Integrity Impact: Low (I:L)
• Availability Impact: Low (A:L)

Threat Level: Medium. The vulnerability allows unauthenticated SSRF, which can be used for internal network reconnaissance and firewall bypass. However, the semi-blind nature limits data exfiltration.

Deep Dive & Mechanics

The vulnerability is a bypass of CVE-2017-0929, which originally addressed SSRF in DNN. The bypass likely involves a different endpoint or parameter that was not properly sanitized. The attacker can craft a malicious GET request to the DNN server, which then forwards the request to an internal or external URL. The response is not fully returned to the attacker, making it semi-blind.

Attack Flow:

1. Attacker sends a crafted HTTP GET request to the vulnerable DNN endpoint.
2. The DNN server processes the request and makes an HTTP GET request to the attacker-specified URL.
3. The response from the target URL is not fully returned to the attacker, but the attacker can infer success or failure based on timing, error messages, or side-channel effects.

Potential Targets:

• Internal network services (e.g., databases, admin panels)
• Cloud metadata endpoints (e.g., AWS http://169.254.169.254/latest/meta-data/)
• Firewall bypass to reach internal systems

Vulnerable vs. Patched Code

The exact vulnerable code is not publicly available, but the patch in version 9.13.8 likely involves:

• Adding input validation for URLs
• Restricting allowed protocols (e.g., only HTTP/HTTPS)
• Blocking requests to private IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
• Implementing a whitelist of allowed domains

Vulnerable Code (Conceptual):

public void MakeRequest(string url)
{
    // No validation of URL
    WebRequest request = WebRequest.Create(url);
    // ...
}

Patched Code (Conceptual):

public void MakeRequest(string url)
{
    if (!IsValidUrl(url))
        throw new ArgumentException("Invalid URL");
    if (IsPrivateIP(url))
        throw new SecurityException("Private IP not allowed");
    WebRequest request = WebRequest.Create(url);
    // ...
}

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Install DNN version 9.13.7 or earlier on a Windows server with IIS.
2. Set up an internal network with a target service (e.g., a simple HTTP server on 192.168.1.100:8080).
3. Use a tool like Burp Suite or a custom script to send the SSRF payload.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /API/SomeEndpoint?url=http://internal-service).
2. Craft a GET request to the DNN server with the target URL.
3. Observe the response or side effects to confirm the request was made.

Example Payload:

GET /API/SomeEndpoint?url=http://192.168.1.100:8080/admin HTTP/1.1
Host: vulnerable-dnn-server.com

Expected Outcome: The DNN server makes a request to the internal service, potentially revealing internal network information.

Blue Team

Detection Steps:

1. Monitor for unusual outbound HTTP requests from the DNN server to internal IPs.
2. Check logs for requests to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).
3. Look for requests to cloud metadata endpoints (e.g., 169.254.169.254).

Hunting Queries:

• Search for URLs containing private IPs in web server logs.
• Monitor for repeated requests to the same internal IP from the DNN server.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound HTTP requests from DNN server to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
  • Requests to cloud metadata endpoints (e.g., http://169.254.169.254/)
  • Unusual User-Agent strings in outbound requests (may be default .NET User-Agent)

• File IOCs:

  • Modified or suspicious entries in DNN log files (e.g., Portals/_default/Logs/)
  • Unexpected entries in IIS logs showing requests to internal IPs

• Behavioral IOCs:

  • DNN server making requests to internal services that it normally does not access
  • Increased latency or errors from internal services due to SSRF probes

Detection Engineering

YARA Rule

rule Detect_DNN_SSRF_CVE_2025_32372 {
    meta:
        description = "Detects potential SSRF exploitation attempts against DNN CVE-2025-32372"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-32372"
    strings:
        $s1 = "url=" nocase
        $s2 = "http://" nocase
        $s3 = "192.168." nocase
        $s4 = "10." nocase
        $s5 = "172." nocase
        $s6 = "169.254." nocase
    condition:
        all of ($s1, $s2) and any of ($s3, $s4, $s5, $s6)
}

Sigma Rule

title: DNN SSRF Exploitation Attempt (CVE-2025-32372)
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential SSRF exploitation attempts against DNN CVE-2025-32372
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-32372
logsource:
    category: webserver
    product: iis
detection:
    selection:
        cs-uri-query|contains:
            - "url=http://10."
            - "url=http://172."
            - "url=http://192.168."
            - "url=http://169.254."
    condition: selection
falsepositives:
    - Legitimate use of URL parameters pointing to internal resources (rare)
level: high

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"CVE-2025-32372 DNN SSRF Exploitation Attempt";
    flow:to_server,established;
    content:"url="; http_uri;
    content:"http://"; http_uri;
    pcre:"/url=http:\/\/(10\.|172\.|192\.168\.|169\.254\.)/Ui";
    reference:cve,2025-32372;
    classtype:attempted-recon;
    sid:10000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Upgrade DNN to version 9.13.8 or later.
2. If immediate upgrade is not possible, implement a Web Application Firewall (WAF) rule to block requests containing private IPs in URL parameters.
3. Restrict outbound HTTP access from the DNN server using network firewalls.

Long-term Mitigations:

1. Apply the principle of least privilege to the DNN application pool account.
2. Monitor logs for SSRF attempts and investigate any suspicious activity.
3. Conduct regular security assessments of the DNN installation.

Workarounds:

• Disable the vulnerable endpoint if it is not required.
• Implement input validation to block requests to private IP ranges.

Valters IT