CVE-2023-30970

Executive Summary

CVE-2023-30970 is a path traversal vulnerability affecting Gotham Table service and Forward App. An authenticated attacker can exploit this flaw to read arbitrary files on the underlying file system, leading to unauthorized disclosure of sensitive data. The vulnerability has a CVSS score of 6.5 (Medium) and is currently unpatched. No public proof-of-concept code or exploit templates are available, but the risk remains significant for organizations using these products.

Supply Chain & Package Security

This vulnerability does not affect NPM, PyPI, Go, or Ruby packages. It is a proprietary application vulnerability in Gotham products.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
• Base Score: 6.5 (Medium)
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (authenticated user)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: None
• Availability Impact: None

The threat level is elevated due to the low complexity and the potential for sensitive data exposure, despite the requirement for authentication.

Deep Dive & Mechanics

The vulnerability resides in the file handling logic of Gotham Table service and Forward App. The applications fail to properly sanitize user-supplied input used to construct file paths. An authenticated attacker can inject path traversal sequences (e.g., ../) to escape the intended directory and read arbitrary files on the server.

The root cause is insufficient validation of file path parameters, allowing directory traversal. This is a classic CWE-22 (Path Traversal) vulnerability. The attack is performed over HTTP/HTTPS, requiring only network access and valid credentials.

Vulnerable vs. Patched Code

Since no official patch is available, the following illustrates the vulnerable pattern and a recommended fix.

Vulnerable Code (Conceptual):

import os

def read_file(filename):
    # No validation of filename
    filepath = os.path.join("/var/data/", filename)
    with open(filepath, 'r') as f:
        return f.read()

Patched Code (Conceptual):

import os

def read_file(filename):
    # Sanitize input: remove path traversal sequences
    safe_filename = os.path.basename(filename)
    filepath = os.path.join("/var/data/", safe_filename)
    # Ensure the resolved path is within the intended directory
    real_path = os.path.realpath(filepath)
    if not real_path.startswith("/var/data/"):
        raise PermissionError("Access denied")
    with open(real_path, 'r') as f:
        return f.read()

Exploitation & Lab Setup

Red Team

Prerequisites:

• Valid credentials for the Gotham Table service or Forward App.
• Network access to the vulnerable endpoint.

Exploitation Steps:

1. Authenticate to the application.
2. Identify an endpoint that accepts a file path parameter (e.g., /api/read?file=report.txt).
3. Inject path traversal sequences to read sensitive files:

   GET /api/read?file=../../../etc/passwd
   

4. The server returns the contents of /etc/passwd.

Example Request:

curl -u username:password "http://target.com/api/read?file=../../../etc/passwd"

Blue Team

Detection:

• Monitor for HTTP requests containing ../ or ..\\ in file path parameters.
• Alert on attempts to access files outside the application's root directory (e.g., /etc/passwd, /etc/shadow, /proc/self/environ).

Hunting:

• Search web server logs for patterns like file=..%2f or file=..%5c.
• Correlate authentication logs with file access anomalies.

Mitigation:

• Implement strict input validation: reject any input containing ../ or ..\\.
• Use a whitelist of allowed file names.
• Run the application with minimal file system permissions.

Indicators of Compromise (IOCs)

• Network:
  • HTTP requests with ../ in query parameters (e.g., file=../../../etc/passwd).
  • Unusual outbound connections from the application server.
• File System:
  • Unexpected access to system files like /etc/passwd, /etc/shadow, or application configuration files.
• Logs:
  • Web server logs showing repeated attempts to access files outside the web root.

Detection Engineering

YARA Rule

rule CVE_2023_30970_Path_Traversal {
    meta:
        description = "Detects path traversal attempts targeting Gotham Table service or Forward App"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2023-30970"
    strings:
        $traversal1 = "../"
        $traversal2 = "..\\"
        $traversal3 = "%2e%2e%2f"
        $traversal4 = "%2e%2e%5c"
        $sensitive1 = "/etc/passwd"
        $sensitive2 = "/etc/shadow"
        $sensitive3 = "/proc/self/environ"
    condition:
        any of ($traversal*) and any of ($sensitive*)
}

Sigma Rule

title: CVE-2023-30970 Path Traversal Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects path traversal attempts in HTTP requests to Gotham Table service or Forward App
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        c-uri|contains:
            - '../'
            - '..\\'
            - '%2e%2e%2f'
            - '%2e%2e%5c'
    condition: selection
falsepositives:
    - Legitimate use of '..' in file paths (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2023-30970 Path Traversal Attempt"; flow:to_server; content:"../"; http_uri; nocase; sid:1000001; rev:1;)
alert http any any -> any any (msg:"CVE-2023-30970 Path Traversal Attempt (encoded)"; content:"%2e%2e%2f"; http_uri; nocase; sid:1000002; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Input Validation: Implement strict validation on all file path parameters. Reject any input containing ../ or ..\\.
2. Access Controls: Ensure the application runs with the least privileges necessary. Restrict file system access to only required directories.
3. Web Application Firewall (WAF): Deploy WAF rules to block path traversal patterns.

Long-Term Fix:

• Apply the official patch from Gotham when released.
• Conduct a code review to identify and fix similar vulnerabilities.
• Implement a secure file handling library that automatically sanitizes paths.

Workaround:

• If patching is not possible, disable the vulnerable functionality or restrict access to trusted users only.

Valters IT