CVE-2017-20248: Apptha Slider Gallery Path Traversal Vulnerability

Technical summary

CVE-2017-20248 is a CWE-22 path traversal vulnerability in Apptha Slider Gallery 1.0. The vulnerability exists in the asgallDownload.php endpoint, which fails to properly sanitize the imgname parameter before constructing a file path. An unauthenticated attacker can inject directory traversal sequences (../) to navigate outside the intended image directory and read arbitrary files accessible to the web server process. The vulnerability carries a CVSS 3.1 score of 7.5 (HIGH) with a vector indicating network-based attack, low complexity, no authentication requirement, and high confidentiality impact.

Business impact

Exploitation of this vulnerability can lead to disclosure of sensitive business data, proprietary code, configuration files containing credentials, database backups, or customer information. Organizations running affected Slider Gallery installations face immediate risk of data exfiltration without requiring any valid credentials or social engineering. In scenarios where configuration files are compromised, attackers may obtain database credentials or API keys enabling further lateral movement or data theft.

Affected systems

Apptha Slider Gallery version 1.0 is affected. Organizations using this WordPress plugin or component should inventory deployments. The vulnerability does not require any specific hosting environment or additional dependencies—any installation exposing asgallDownload.php to the network is vulnerable.

Exploitability

This vulnerability has low attack complexity and requires only network access and an unauthenticated HTTP request. No special tools or exploits are needed; a simple GET or POST request with traversal sequences in the imgname parameter is sufficient. The attack surface is immediate and continuous for any publicly accessible instance, making it a high-priority target for opportunistic scanning and automated exploitation.

Remediation

Organizations must immediately update Apptha Slider Gallery to a patched version that properly validates and sanitizes the imgname parameter (verify the specific version number against the vendor advisory). As an interim measure, restrict access to asgallDownload.php using web application firewall rules or .htaccess configurations to block requests containing ../ sequences, or disable the plugin entirely if unused. Conduct a file integrity audit to detect whether sensitive files have been accessed or downloaded.

Patch guidance

Contact Apptha or check their official plugin repository for a security update addressing CWE-22 path traversal. When available, apply the patched version immediately. Verify the fix by testing that directory traversal sequences in the imgname parameter are rejected. Consider enabling detailed logging on asgallDownload.php requests to detect exploitation attempts.

Detection guidance

Monitor web server access logs for requests to asgallDownload.php containing directory traversal patterns (../ or encoded variants such as %2e%2e%2f). Flag any successful file downloads outside the intended image directory. Implement network-based detection rules to alert on traversal sequences in the imgname parameter. Review file access logs for unexpected reads of sensitive files (configuration files, database files, or source code) coinciding with web requests.

Why prioritize this

With a CVSS score of 7.5 (HIGH), unauthenticated remote access, and no user interaction required, this vulnerability poses an immediate confidentiality threat. The simplicity of exploitation combined with the likelihood of automated scanning makes this a critical priority for rapid patching or mitigation, especially for internet-facing installations.

Risk score, explained

The CVSS 3.1 score of 7.5 reflects a network-based attack (AV:N) with low complexity (AC:L), requiring no privileges (PR:N) or user interaction (UI:N). The scope is unchanged (S:U), but the confidentiality impact is high (C:H), meaning sensitive data can be directly accessed. Integrity and availability are not impacted by this vulnerability alone. The high score reflects the ease and directness of exploitation against publicly exposed instances.

Frequently asked questions