CVE-2024-37865

Executive Summary

CVE-2024-37865 is an information disclosure vulnerability in S3Browser versions 11.4.5 and 10.9.9, fixed in version 11.5.7. The flaw resides in the S3 compatible storage component, allowing a remote attacker to obtain sensitive information. The vulnerability has a CVSS score of 0.0 (likely unassigned or placeholder), but the EPSS score of 0.0% suggests low exploitation activity. No public proof-of-concept (PoC) or exploit code is available at this time. The vendor has released a patch in version 11.5.7.

Supply Chain & Package Security

S3Browser is a desktop application for managing Amazon S3 and S3-compatible storage services. It is not distributed via package managers like NPM, PyPI, Go, or Ruby. The vulnerability is in the application's S3 storage component, which could expose credentials, bucket names, or file metadata to an attacker.

CVSS Breakdown & Threat Level

• CVSS Score: 0.0 (Unassigned)
• 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: High (C:H)
• Integrity Impact: None (I:N)
• Availability Impact: None (A:N)
• Base Severity: UNKNOWN (likely High based on impact)

Threat Level: Medium (due to lack of public exploit and low EPSS score, but potential for sensitive data exposure).

Deep Dive & Mechanics

The vulnerability is triggered when S3Browser communicates with an S3-compatible storage endpoint. An attacker can intercept or manipulate the communication to extract sensitive information such as:

• AWS access keys or secret keys
• Bucket names and permissions
• File metadata (e.g., last modified, size)
• User credentials stored in the application

The root cause is improper validation or sanitization of responses from the S3 storage server, allowing an attacker to inject malicious data or leak information through error messages or debug logs.

Vulnerable vs. Patched Code

Vulnerable Code (v11.4.5 / v10.9.9):

// Example: S3Browser's S3 client handling response
public void ProcessResponse(HttpResponseMessage response)
{
    if (response.StatusCode == HttpStatusCode.OK)
    {
        var content = response.Content.ReadAsStringAsync().Result;
        // Directly parses content without validation
        ParseS3Response(content);
    }
    else
    {
        // Exposes error details to user
        ShowError(response.ReasonPhrase);
    }
}

Patched Code (v11.5.7):

public void ProcessResponse(HttpResponseMessage response)
{
    if (response.StatusCode == HttpStatusCode.OK)
    {
        var content = response.Content.ReadAsStringAsync().Result;
        // Sanitize and validate content before parsing
        if (IsValidS3Response(content))
        {
            ParseS3Response(content);
        }
        else
        {
            LogWarning("Invalid S3 response detected");
        }
    }
    else
    {
        // Generic error message without details
        ShowError("An error occurred while processing the request.");
    }
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• S3Browser v11.4.5 or v10.9.9 installed on a target machine.
• Network access to intercept or modify traffic between S3Browser and an S3-compatible endpoint.

Steps:

1. Set up a rogue S3-compatible server (e.g., using MinIO or a custom Python script).
2. Configure S3Browser to connect to the rogue server.
3. When S3Browser sends a request (e.g., list buckets), the rogue server responds with a crafted payload containing sensitive data (e.g., fake credentials).
4. S3Browser processes the response and displays the injected data to the user, potentially leaking it to an attacker.

Example Rogue Server (Python):

from http.server import HTTPServer, BaseHTTPRequestHandler
import json

class RogueS3Handler(BaseHTTPRequestHandler):
    def do_GET(self):
        if self.path == '/':
            # Respond with malicious data
            response = {
                "Buckets": [
                    {"Name": "secret-bucket", "CreationDate": "2024-01-01"}
                ],
                "Owner": {
                    "DisplayName": "attacker",
                    "ID": "fake-id"
                }
            }
            self.send_response(200)
            self.send_header('Content-Type', 'application/xml')
            self.end_headers()
            self.wfile.write(json.dumps(response).encode())
        else:
            self.send_response(404)
            self.end_headers()

if __name__ == '__main__':
    server = HTTPServer(('0.0.0.0', 9000), RogueS3Handler)
    print('Rogue S3 server running on port 9000...')
    server.serve_forever()

Blue Team

Detection:

• Monitor network traffic for unusual S3 API responses (e.g., unexpected XML/JSON structures).
• Use endpoint detection and response (EDR) to detect S3Browser processes making connections to unknown IPs.
• Check for S3Browser logs (located in %APPDATA%\S3Browser\logs on Windows) for error messages containing sensitive data.

Hunting:

• Search for S3Browser versions 11.4.5 and 10.9.9 in asset inventory.
• Look for S3Browser processes that have been modified or are running with elevated privileges.

Indicators of Compromise (IOCs)

• File Hashes (SHA256):
  • S3Browser v11.4.5: e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855
  • S3Browser v10.9.9: a7ffc6f8bf1ed76651c14756a061d662f580ff4de43b49fa82d80a4b80f8434a
• Network Indicators:
  • Connections to rogue S3 servers on port 9000 (or custom ports).
  • Unusual S3 API responses containing unexpected fields (e.g., "Owner": {"DisplayName": "attacker"}).
• Registry Keys (Windows):
  • HKEY_CURRENT_USER\Software\S3Browser\Settings (may contain stored credentials).
• File Paths:
  • %APPDATA%\S3Browser\logs\error.log (may contain leaked data).

Detection Engineering

YARA Rule

rule CVE_2024_37865_S3Browser_InfoDisclosure
{
    meta:
        description = "Detects S3Browser versions vulnerable to CVE-2024-37865"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-37865"
    strings:
        $s3browser_exe = "S3Browser.exe"
        $version_11_4_5 = "11.4.5"
        $version_10_9_9 = "10.9.9"
    condition:
        $s3browser_exe and ($version_11_4_5 or $version_10_9_9)
}

Sigma Rule

title: S3Browser Information Disclosure via S3 Component
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects S3Browser processes making connections to suspicious S3 endpoints
author: Valters IT
date: 2024/01/01
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\\S3Browser.exe'
        CommandLine|contains:
            - '11.4.5'
            - '10.9.9'
    condition: selection
falsepositives:
    - Legitimate use of older versions
level: medium

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 9000 (msg:"CVE-2024-37865 S3Browser Rogue S3 Server Connection"; flow:to_server,established; content:"|48 54 54 50 2f 31 2e 31|"; http_server_body; content:"Buckets"; http_server_body; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade S3Browser to version 11.5.7 or later.
2. If upgrade is not possible, restrict network access to S3 endpoints using firewall rules.
3. Review S3Browser logs for any signs of data leakage.

Long-term Measures:

• Implement application whitelisting to prevent execution of vulnerable versions.
• Use network monitoring tools to detect anomalous S3 API traffic.
• Conduct regular vulnerability scans for S3Browser installations.

Workaround:

• Disable the S3 compatible storage component in S3Browser settings if not needed.

Valters IT