CVE-2024-4219

Executive Summary

CVE-2024-4219 is a Server-Side Request Forgery (SSRF) vulnerability in BeyondTrust's BeyondInsight platform, affecting versions prior to 23.2. The flaw allows an authenticated attacker with low privileges to craft arbitrary HTTP requests from the vulnerable server via HTTP-based connectors. This can lead to internal network reconnaissance, access to cloud metadata endpoints, or interaction with internal services that are not intended to be exposed. The CVSS score is 4.8 (Medium), and while no public proof-of-concept or exploit code has been released, the attack surface is significant for organizations using BeyondInsight for privileged access management.

Supply Chain & Package Security

This vulnerability is not related to an open-source package manager (NPM, PyPI, Go, Ruby). It affects a proprietary enterprise software product, BeyondInsight, which is distributed as a compiled application. The risk is primarily to the deploying organization's internal network and cloud infrastructure.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
• Base Score: 4.8 (Medium)
• Attack Vector (AV): Network – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): Low – An attacker needs a valid low-privilege account on BeyondInsight.
• User Interaction (UI): None – No user action is required.
• Scope (S): Unchanged – The vulnerable component and the affected resource are the same.
• Confidentiality (C): Low – Limited information disclosure (e.g., internal service banners, cloud metadata).
• Integrity (I): Low – Limited ability to modify data (e.g., writing to internal services).
• Availability (A): None – No impact on system availability.

Threat Level: Medium. While the CVSS score is moderate, the SSRF nature can be chained with other vulnerabilities (e.g., internal service exploitation) to achieve higher impact.

Deep Dive & Mechanics

The vulnerability resides in the HTTP-based connector functionality of BeyondInsight. These connectors are designed to fetch data from external or internal HTTP endpoints for integration purposes. Due to insufficient validation of user-supplied URLs, an authenticated attacker can manipulate the connector to send requests to arbitrary internal IP addresses and ports.

Attack Flow:

1. Authentication: The attacker logs into BeyondInsight with a low-privilege account.
2. Connector Manipulation: The attacker creates or modifies an HTTP-based connector, specifying a malicious URL (e.g., http://169.254.169.254/latest/meta-data/ for AWS cloud metadata).
3. Request Execution: BeyondInsight processes the connector and sends an HTTP request to the attacker-specified target.
4. Data Exfiltration: The response from the internal service is returned to the attacker via the connector's output or error messages.

Root Cause: The application fails to validate that the target URL is within an allowed whitelist or that it does not resolve to internal/private IP ranges (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16, 127.0.0.0/8, 169.254.0.0/16).

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

def execute_connector(url):
    # No validation of URL
    response = requests.get(url)
    return response.text

Patched Code (Conceptual):

import ipaddress
from urllib.parse import urlparse

def is_private_ip(hostname):
    try:
        ip = ipaddress.ip_address(hostname)
        return ip.is_private or ip.is_loopback or ip.is_link_local
    except ValueError:
        # Hostname is not an IP, could be DNS; additional validation needed
        return False

def execute_connector(url):
    parsed = urlparse(url)
    if is_private_ip(parsed.hostname):
        raise ValueError("URL points to a private IP range")
    # Additional whitelist checks
    response = requests.get(url)
    return response.text

The patch introduces IP address validation to block requests to private, loopback, and link-local addresses. It also recommends implementing a whitelist of allowed external domains.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A low-privilege account on BeyondInsight (version < 23.2).
• Network access to the BeyondInsight server.

Exploitation Steps:

1. Log in to BeyondInsight.
2. Navigate to the HTTP-based connector configuration.
3. Create a new connector with the following payload:
   • URL: http://169.254.169.254/latest/meta-data/iam/security-credentials/admin
   • Method: GET
4. Execute the connector.
5. Observe the response, which may contain AWS IAM credentials.

Alternative Targets:

• Internal web applications: http://internal-app:8080/admin
• Database endpoints: http://db-server:5432
• Cloud metadata: http://100.100.100.200/latest/meta-data/ (Alibaba Cloud)

Lab Setup:

• Deploy BeyondInsight version 23.1 in a controlled environment.
• Set up a simple HTTP server on an internal IP (e.g., 10.0.0.5:8080) to simulate an internal service.
• Use a low-privilege account to trigger the SSRF and capture the request.

Blue Team (Defensive)

Detection:

• Monitor BeyondInsight logs for unusual connector activity, especially requests to private IP ranges.
• Use network monitoring to detect outbound HTTP requests from the BeyondInsight server to internal IPs.
• Implement a Web Application Firewall (WAF) rule to block requests containing private IP addresses in the URL parameter.

Hunting:

• Search for connector configurations with URLs pointing to internal IPs or cloud metadata endpoints.
• Review historical logs for any connector executions that returned data from unexpected sources.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound HTTP requests from BeyondInsight to private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).
  • Requests to cloud metadata IPs (169.254.169.254, 100.100.100.200).
  • Unusual HTTP response sizes from internal services.

• Log IOCs:

  • BeyondInsight audit logs showing connector executions with URLs containing private IPs.
  • Error logs indicating connection attempts to unreachable internal hosts.

• File IOCs:

  • Connector configuration files containing suspicious URLs (e.g., connector_config.xml with <url>http://10.0.0.1</url>).

Detection Engineering

YARA Rule

rule CVE_2024_4219_SSRF_Connector {
    meta:
        description = "Detects BeyondInsight connector configurations with SSRF indicators"
        author = "Valters IT"
        date = "2024-10-27"
        reference = "CVE-2024-4219"
    strings:
        $url_private = /http:\/\/(10\.|172\.(1[6-9]|2[0-9]|3[01])\.|192\.168\.|127\.|169\.254\.|0\.)/
        $url_metadata = /http:\/\/169\.254\.169\.254/
        $connector_tag = "<connector"
    condition:
        $connector_tag and any of ($url_private, $url_metadata)
}

Sigma Rule

title: BeyondInsight SSRF via HTTP Connector
id: 7a8b3c4d-5e6f-4a7b-8c9d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests from BeyondInsight to private IP ranges, indicating SSRF exploitation.
author: Valters IT
date: 2024-10-27
logsource:
    category: network
    product: beyondtrust
detection:
    selection:
        destination.ip:
            - '10.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
            - '127.0.0.0/8'
            - '169.254.0.0/16'
        source.port: 443
    condition: selection
falsepositives:
    - Legitimate internal integrations (should be whitelisted)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-4219 BeyondInsight SSRF Attempt"; flow:to_server; content:"GET"; http_method; content:"/latest/meta-data/"; http_uri; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade: Update BeyondInsight to version 23.2 or later, which includes the fix for this vulnerability.
2. Network Segmentation: Restrict outbound HTTP access from the BeyondInsight server to only necessary external services using a firewall or egress proxy.
3. Access Control: Review and minimize the number of low-privilege accounts that can create or modify connectors.

Long-Term Measures:

• Implement a URL whitelist for HTTP-based connectors.
• Deploy a Web Application Firewall (WAF) with rules to block SSRF attempts.
• Conduct regular security audits of connector configurations.
• Monitor BeyondInsight logs for anomalous connector activity.

Workaround (if patching is delayed):

• Disable HTTP-based connectors if not in use.
• Apply strict network ACLs to prevent the BeyondInsight server from reaching internal IP ranges.

Valters IT
Securing Your Digital Frontier