CVE-2023-41830

Executive Summary

CVE-2023-41830 is an improper absolute path traversal vulnerability in the Ready For application. This flaw allows a local application to access files outside its intended directory without proper authorization. The vulnerability has a CVSS score of 6.5 (Medium) and is currently unpatched. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the risk remains for local privilege escalation or data exfiltration.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It affects a standalone application (Ready For) and does not involve package manager dependencies.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Local (L) – The attacker must have local access to the system.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs low-level privileges.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality (C): High (H) – Full file read access possible.
• Integrity (I): None (N) – No file modification.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. Local exploitation could lead to unauthorized file access, potentially exposing sensitive data.

Deep Dive & Mechanics

The vulnerability is an improper absolute path traversal (CWE-22). The Ready For application fails to properly sanitize file paths when handling requests from local applications. An attacker with local access can craft a request containing absolute path sequences (e.g., C:\Windows\System32\config\SAM or /etc/shadow) to read arbitrary files on the system.

The root cause is likely insufficient validation of user-supplied paths before file operations. The application may use functions like File.ReadAllText() or open() without checking if the resolved path stays within an allowed base directory.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern:

Vulnerable (pseudocode):

def read_file(user_path):
    # No path validation
    return open(user_path).read()

Patched (pseudocode):

import os

ALLOWED_DIR = "/var/readyfor/data/"

def read_file(user_path):
    # Resolve absolute path and check prefix
    full_path = os.path.abspath(user_path)
    if not full_path.startswith(ALLOWED_DIR):
        raise PermissionError("Access denied")
    return open(full_path).read()

Exploitation & Lab Setup

Red Team

Prerequisites: Local access to a system running the vulnerable Ready For application.

Exploit Steps:

1. Identify the Ready For application process and its file access API.
2. Craft a request with an absolute path to a sensitive file, e.g., C:\Windows\System32\drivers\etc\hosts (Windows) or /etc/passwd (Linux).
3. Send the request to the application's local endpoint.
4. Retrieve the file contents.

Example (Linux):

curl --unix-socket /var/run/readyfor.sock http://localhost/read?file=/etc/shadow

Example (Windows):

Invoke-WebRequest -Uri "http://localhost:8080/read?file=C:\Windows\System32\config\SAM"

Blue Team

Detection:

• Monitor for file access patterns that deviate from the application's normal behavior.
• Look for requests containing absolute paths (e.g., C:\, /etc/, /proc/).
• Use file integrity monitoring to detect unauthorized reads of sensitive files.

Hunting:

• Search logs for the Ready For application accessing files outside its installation directory.
• Correlate with process creation events for suspicious local applications.

Indicators of Compromise (IOCs)

• File Paths: Any request to the Ready For application containing absolute paths like C:\Windows\System32\, /etc/, /proc/, /sys/.
• Process Names: readyfor.exe or readyfor with unusual file handles.
• Network Connections: Local connections to the Ready For service (e.g., 127.0.0.1:8080 or Unix socket).
• Log Entries: Error messages indicating path traversal attempts (e.g., "Access denied" or "File not found" for sensitive paths).

Detection Engineering

YARA Rule

rule CVE_2023_41830_PathTraversal {
    meta:
        description = "Detects path traversal attempts against Ready For application"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2023-41830"
    strings:
        $s1 = "C:\\" ascii wide nocase
        $s2 = "/etc/" ascii wide nocase
        $s3 = "/proc/" ascii wide nocase
        $s4 = "/sys/" ascii wide nocase
        $s5 = "..\\" ascii wide nocase
        $s6 = "../" ascii wide nocase
    condition:
        any of ($s*) and filesize < 10KB
}

Sigma Rule

title: CVE-2023-41830 Ready For Path Traversal
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects path traversal attempts against Ready For application
author: Valters IT
date: 2025-04-10
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        Image|endswith: '\readyfor.exe'
        CommandLine|contains:
            - 'C:\'
            - '/etc/'
            - '/proc/'
            - '/sys/'
            - '..\'
            - '../'
    condition: selection
falsepositives:
    - Legitimate file access within allowed directories
level: high

Suricata Rule

alert tcp any any -> any any (msg:"CVE-2023-41830 Ready For Path Traversal"; flow:to_server; content:"/read?file="; nocase; content:"C:\\"; distance:0; within:100; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Restrict local access to the Ready For application using firewall rules or Unix socket permissions.
2. Implement application-level path validation to ensure all file operations are confined to a specific directory.
3. Monitor logs for suspicious file access patterns.

Long-term Fix:

• Apply vendor patch when available.
• Consider replacing the application with a more secure alternative if no patch is forthcoming.

Workaround:

• Use filesystem permissions to restrict the application's access to sensitive directories.
• Run the application in a sandboxed environment (e.g., container, AppArmor, SELinux).

Valters IT