CVE-2018-7602: Drupal Core Remote Code Execution Vulnerability

CVE-2018-7602 is a remote code execution vulnerability in Drupal Core. According to CISA, it exists within multiple subsystems and can allow attackers to exploit multiple attack vectors on a Drupal site. It matters because successful exploitation can let an unauthenticated or low-privilege attacker run arbitrary code on the server, fully compromising the site and the host it runs on. Public reporting also indicates this vulnerability has been used by ransomware operators, elevating the urgency for any organization still running affected Drupal installations.

How it works

The underlying weakness is remote code execution affecting multiple subsystems inside Drupal Core. In broad terms for this class of flaw, an attacker crafts requests that reach vulnerable code paths—often involving how Drupal processes certain forms, render arrays, or other internal APIs—and causes the application to evaluate or execute attacker-controlled data as code. Because the vulnerability spans more than one subsystem, there can be several distinct attack vectors rather than a single narrow entry point. Exact request formats, required conditions, and whether authentication is needed are not detailed in the provided facts; defenders must confirm those mechanics against the vendor advisory. Once code execution is achieved, the attacker typically gains the privileges of the web-server user and can install backdoors, steal data, or deploy further payloads, including ransomware.

Am I affected? How to find it in your systems

Drupal Core is the foundation of sites built with the Drupal content-management system. It commonly runs on Linux web servers (Apache, Nginx, or similar) with PHP, often behind reverse proxies or load balancers, and may appear in development, staging, and production environments as well as in container images or platform-as-a-service offerings.

• Inventory every web property and internal tool that could be Drupal: check HTTP response headers, generator meta tags, common paths such as /core/, /sites/default/, and the presence of Drupal-specific files or modules.
• On hosts you control, locate Drupal installations by searching for characteristic files (for example, core/lib/Drupal.php or CHANGELOG.txt) and record the installed core version.
• Compare those versions against the fixed releases listed in the official Drupal security advisory for CVE-2018-7602; do not rely on version ranges stated elsewhere.
• Review web-server and application logs for anomalous POST or GET requests that coincide with unexpected PHP errors, new administrative users, modified files under the Drupal root, or outbound connections initiated by the web-server process—common telemetry signs after RCE exploitation. Confirm any indicators with the vendor’s guidance.

How to remediate

The primary action required by CISA is to apply updates per vendor instructions. Obtain the official Drupal Core security release that addresses CVE-2018-7602 and deploy it through your normal change process—test first in a non-production environment, then roll out to production as quickly as possible. After patching, verify the running version and consider a full file-integrity check of the Drupal root to ensure no residual web shells or unauthorized modifications remain. As general hardening for this class of vulnerability, keep Drupal core and contributed modules current, remove unused modules, enforce least-privilege file permissions, and ensure the PHP process cannot write to code directories.

If you can't patch immediately

If an immediate upgrade is impossible, reduce exposure with compensating controls while you prepare the patch:

• Segment the Drupal hosts so they are unreachable from untrusted networks except through a tightly controlled reverse proxy or WAF.
• Apply virtual patching rules on a web application firewall that block the request patterns associated with known exploit attempts for this CVE; tune and monitor for false positives.
• Disable or restrict any non-essential Drupal subsystems or modules that are not required for business function, thereby shrinking the attack surface.
• Increase monitoring: alert on unusual process execution by the web-server user, unexpected file changes under the document root, and anomalous outbound traffic. Retain logs for forensic review.
• If feasible, place the site in maintenance mode or temporarily take it offline until the vendor update can be applied.

These measures only buy time; they do not replace the vendor patch.

If your data may have been exposed

Actively exploited remote-code-execution vulnerabilities, especially those with known ransomware use, frequently lead to data theft or encryption. If you discover evidence of compromise or simply cannot rule it out, treat the incident as a potential breach: isolate affected systems, preserve logs and disk images, and follow your incident-response plan. As one quick external check, you can run a free exposure scan of your email addresses against known breach data sets to see whether credentials or personal information have already appeared in public dumps. Continue to monitor for ransomware notes, unusual encryption activity, or extortion communications while remediation and forensics proceed.