CVE-2018-25409: SIM-PKH 2.4.1 Arbitrary File Upload Leading to Remote Code Execution

Technical summary

CVE-2018-25409 is an arbitrary file upload vulnerability in SIM-PKH 2.4.1 affecting the aksi_pengurus.php endpoint. The vulnerability exists because the application fails to properly validate file uploads submitted through the fupload parameter when module=pengurus and act=update parameters are set. Uploaded files are stored directly in the foto directory without adequate type checking or sanitization. An authenticated attacker can upload PHP files that are then executed by the web server with the privileges of the application process, resulting in remote code execution (RCE). The vulnerability maps to CWE-434 (Unrestricted Upload of File with Dangerous Type).

Business impact

Successful exploitation allows an authenticated attacker to execute arbitrary code on the web server, leading to complete system compromise. This enables attackers to steal sensitive data, modify application functionality, deploy malware or backdoors, or use the compromised server as a pivot point for lateral movement within the network. Organizations running SIM-PKH 2.4.1 in production environments face significant operational and data security risk, particularly if the application handles sensitive business or user information.

Affected systems

SIM-PKH version 2.4.1 is affected. Organizations should inventory systems running this version, with particular attention to internet-facing or otherwise accessible instances. Verify whether your deployment includes the vulnerable aksi_pengurus.php endpoint and whether it is accessible to authenticated users. No vendor patch information is currently referenced; contact the SIM-PKH vendor or project maintainers for remediation guidance and available updates.

Exploitability

The vulnerability requires valid authentication credentials, which limits its initial attack surface compared to unauthenticated exploits. However, the network attack vector combined with low complexity makes exploitation straightforward for any authenticated user. No special conditions or user interaction are required once access is obtained. The attack is reliable and deterministic. Insider threats or compromised credentials pose the most immediate risk vector; external attackers would need to first breach authentication.

Remediation

Organizations should immediately upgrade SIM-PKH to a patched version released by the vendor. If an update is not yet available, implement compensating controls: restrict access to the aksi_pengurus.php endpoint at the network or application level, disable file upload functionality if not essential, enforce strict file type validation, configure the web server to prevent PHP execution in the foto directory (via .htaccess, nginx configuration, or similar), and implement robust authentication controls and monitoring. Verify that the foto directory and its contents have appropriate file system permissions.

Patch guidance

Contact the SIM-PKH vendor or project maintainers to obtain the latest patched version addressing this vulnerability. Verify the specific version number against the vendor's security advisory before deployment. Test patches in a non-production environment before rolling out to production systems. If a patch is not yet available, apply the compensating controls listed in the remediation section and establish a timeline with the vendor for an official fix. Monitor the vendor's security communications for updates.

Detection guidance

Monitor HTTP POST requests to aksi_pengurus.php with parameters module=pengurus and act=update; flag requests containing file uploads or suspicious parameter values. Inspect the foto directory for recently created or modified PHP files, particularly those with unusual names or timestamps corresponding to suspected compromise periods. Review web server access and error logs for execution of PHP scripts from the foto directory. Implement file integrity monitoring on this directory. Check for unusual process spawning or outbound connections initiated from the web server process around times of suspicious uploads. Log all file uploads including user, timestamp, filename, and content type for forensic review.

Why prioritize this

This vulnerability merits immediate attention despite requiring authentication, due to its HIGH CVSS score (8.8) and the severity of potential impact—remote code execution with full system compromise. Authenticated attacks are realistic vectors, especially given insider threats, credential compromise through phishing or data breaches, and weak authentication implementations. The simplicity of exploitation and wide availability of exploitation tools for such vulnerabilities means this should be treated with high priority in patch management workflows.

Risk score, explained

The CVSS 3.1 score of 8.8 (HIGH) reflects: Network attack vector (AV:N) allowing remote exploitation, Low attack complexity (AC:L) requiring no special conditions, authentication requirement (PR:L) reducing but not eliminating risk, no user interaction needed (UI:N), and high impact across confidentiality, integrity, and availability (C:H/I:H/A:H). The score appropriately captures the severity of unauthenticated remote code execution; however, the authentication prerequisite should inform your risk assessment alongside organizational access controls and credential hygiene.

Frequently asked questions