CVE-2024-41726

Executive Summary

CVE-2024-41726 is a path traversal vulnerability in SKYSEA Client View, a Japanese endpoint management solution. The flaw exists in versions 3.013.00 through 19.210.04e. An authenticated user with local access to a Windows client can exploit this to execute arbitrary executables by manipulating file paths. No public proof-of-concept or patch is currently available. The vulnerability is classified as a path traversal (CWE-22) and requires local user authentication, limiting remote exploitation but posing significant risk in shared or multi-user environments.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary Windows client application (SKYSEA Client View). No supply chain package security implications are identified.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0 in the NVD data, indicating incomplete scoring. Based on the description, a reasonable assessment would be:

• Attack Vector (AV): Local (L) – requires user login to the PC.
• Attack Complexity (AC): Low (L) – path traversal is straightforward.
• Privileges Required (PR): Low (L) – user-level access needed.
• User Interaction (UI): None (N) – no additional user action beyond login.
• Scope (S): Unchanged (U) – exploitation stays within the same security authority.
• Confidentiality (C): High (H) – arbitrary executable execution can lead to data theft.
• Integrity (I): High (H) – arbitrary code execution compromises system integrity.
• Availability (A): High (H) – can disrupt system operations.

Estimated CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Estimated Base Score: 7.8 (High)

Threat Level: High – due to the potential for arbitrary code execution with low privileges.

Deep Dive & Mechanics

The vulnerability is a classic path traversal (directory traversal) in SKYSEA Client View. The software likely handles file paths for configuration, updates, or log files without proper sanitization. An authenticated user can supply a path containing ../ sequences to escape the intended directory and reference an arbitrary executable file (e.g., ..\..\Windows\System32\cmd.exe). When the client processes this path, it executes the referenced file with the privileges of the SKYSEA Client View process, which may run as SYSTEM or a high-integrity account.

Root Cause: Insufficient validation of user-supplied file paths in the client application. The software fails to canonicalize paths or restrict them to a safe base directory.

Attack Flow:

1. Attacker logs into a Windows machine where SKYSEA Client View is installed.
2. Attacker identifies a feature that accepts a file path (e.g., custom script execution, log viewer, update mechanism).
3. Attacker provides a malicious path like ..\..\Windows\System32\malware.exe.
4. The client resolves the path and executes the file, leading to arbitrary code execution.

Vulnerable vs. Patched Code

No patch is available. The vulnerable code likely resembles:

// Vulnerable pseudo-code
string userInput = GetUserInput("Enter file path:");
string fullPath = Path.Combine(baseDirectory, userInput);
Process.Start(fullPath);

A patched version would include path validation:

// Patched pseudo-code
string userInput = GetUserInput("Enter file path:");
string fullPath = Path.GetFullPath(Path.Combine(baseDirectory, userInput));
if (!fullPath.StartsWith(baseDirectory, StringComparison.OrdinalIgnoreCase))
{
    throw new SecurityException("Invalid path.");
}
Process.Start(fullPath);

Exploitation & Lab Setup

Red Team

Prerequisites:

• Windows machine with SKYSEA Client View (v3.013.00 to v19.210.04e) installed.
• Local user account (non-admin may suffice).

Exploitation Steps:

1. Identify the vulnerable feature (e.g., custom script execution or log file viewer).
2. Craft a path traversal payload:

   ..\..\Windows\System32\calc.exe
   

3. Submit the payload through the client interface.
4. Observe execution of calc.exe (or a custom payload).

Example Payload (if feature accepts a file path via command line):

SKYSEAClient.exe --execute "..\..\Windows\System32\cmd.exe /c whoami > C:\temp\output.txt"

No public exploit code is available.

Blue Team

Detection:

• Monitor for unusual file path patterns in SKYSEA Client View logs (e.g., ..\ sequences).
• Use Sysmon to track process creation events where the parent process is SKYSEAClient.exe and the child is an unexpected executable (e.g., cmd.exe, powershell.exe).
• Enable Windows Event ID 4688 (Process Creation) and filter for SKYSEAClient.exe as parent.

Hunting Query (KQL):

DeviceProcessEvents
| where InitiatingProcessFileName == "SKYSEAClient.exe"
| where FileName in~ ("cmd.exe", "powershell.exe", "wscript.exe", "cscript.exe", "regsvr32.exe")
| project Timestamp, DeviceName, InitiatingProcessFileName, FileName, ProcessCommandLine

Indicators of Compromise (IOCs)

• File Paths: Any path containing ..\ submitted to SKYSEA Client View.
• Process Tree: SKYSEAClient.exe spawning cmd.exe, powershell.exe, or other unexpected binaries.
• Registry Keys: (Potential persistence) HKCU\Software\Microsoft\Windows\CurrentVersion\Run with a reference to a malicious executable.
• Network Connections: Outbound connections from spawned processes (e.g., C2 traffic).

Detection Engineering

YARA Rule

rule CVE_2024_41726_SKYSEA_PathTraversal {
    meta:
        description = "Detects path traversal attempts in SKYSEA Client View logs or memory"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-41726"
    strings:
        $traversal1 = "..\\" ascii wide nocase
        $traversal2 = "../" ascii wide nocase
        $skysea = "SKYSEA" ascii wide nocase
    condition:
        $skysea and any of ($traversal*)
}

Sigma Rule

title: CVE-2024-41726 SKYSEA Client View Path Traversal
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects path traversal attempts in SKYSEA Client View logs
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-41726
logsource:
    product: windows
    service: application
detection:
    selection:
        EventID: 4688
        ParentProcessName|endswith: '\\SKYSEAClient.exe'
        ProcessCommandLine|contains: '..\\'
    condition: selection
falsepositives:
    - Legitimate use of relative paths in scripts
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-41726 SKYSEA Client View Path Traversal"; flow:to_server,established; content:"..\\"; http_uri; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected systems: Disconnect machines running vulnerable SKYSEA Client View from untrusted networks.
2. Restrict local user privileges: Limit user accounts to prevent exploitation (though the vulnerability requires authentication).
3. Monitor logs: Enable detailed logging for SKYSEA Client View and Windows process creation.

Long-term Fix:

• Vendor patch: Await an official patch from Skysea. Contact Skysea support for updates.
• Workaround: If possible, disable the vulnerable feature (e.g., custom script execution) via group policy or configuration.
• Upgrade: Upgrade to a patched version once released (check Skysea's website).

Compensating Controls:

• Deploy application whitelisting (e.g., AppLocker) to block execution of unauthorized binaries.
• Use endpoint detection and response (EDR) to alert on suspicious process chains.

Valters IT
DevSecOps & Cyber Threat Intelligence