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CVE-2018-7602 (Drupal Core Remote Code Execution)

CVE-2018-7602 is a remote code execution vulnerability in Drupal Core. CISA added it to the Known Exploited Vulnerabilities catalogue on 13 April 2022, which means attackers have used it in real attacks. A remote code execution vulnerability exists within multiple subsystems of Drupal that can allow attackers to exploit multiple attack vectors on a Drupal site.

How this vulnerability behaves in Drupal Core

CVE-2018-7602 is dangerous because remote code execution in a content management system can turn a web-facing application into a full server compromise. In Drupal Core, that means an attacker may move from a crafted request to executing code in the application context, which can expose data, alter content, and create a foothold for broader compromise.

The practical significance is not just that the bug exists, but that multiple subsystems and attack vectors can make exposure harder to reason about. An organisation should treat the issue as a platform-level weakness rather than a single-page defect, because the exploit path may vary with site design, installed modules, and how the application is reachable from the internet.

Why this kind of flaw is high impact

Remote code execution is one of the most severe vulnerability classes in a web application because it can collapse the boundary between user input and server-side execution. Once that boundary fails, attackers may be able to read configuration files, plant web shells, create new users, tamper with pages, or pivot into adjacent infrastructure that the web server can reach.

For Drupal sites, the impact often extends beyond the application itself. A compromised CMS may expose database credentials, API keys, SMTP secrets, or session material stored in configuration or environment data, which can then be reused to reach other services. That makes the business impact larger than content defacement alone.

How organisations should assess exposure

Exposure checking starts with a trustworthy asset inventory, because you cannot protect what you do not know you run. Identify every internet-facing Drupal instance, every internal administrative instance, and every cloned or forgotten environment, then compare them against vendor advisory guidance and the CISA KEV catalogue entry for this CVE. For broader prioritisation and verification discipline, NHIMG’s Vulnerability Management Guide is useful for framing scope, prioritisation, and remediation confirmation.

Check for reverse proxies, load balancers, application firewalls, and delegated hosting arrangements that may obscure where the vulnerable application actually sits. If a site is publicly reachable, assume it is a priority target until proven otherwise, and validate whether all affected application paths are covered by patching, compensating controls, or temporary isolation.

Remediation, detection, and compromise review

The primary response is to apply the vendor’s remediation guidance as soon as possible and then verify that the application is no longer exposed to the vulnerable path. Where immediate patching is not possible, reduce exposure by restricting internet access, hardening administrative reachability, limiting execution paths, and increasing monitoring around the affected host and web tier.

Detection should focus on signs that the flaw was exercised before patching. Review web logs for unusual requests, suspicious parameter patterns, unexpected POST activity, and follow-on indicators such as new files, altered configuration, unfamiliar admin accounts, or outbound connections from the server. After remediation, perform a post-patch compromise review because exploit success may not be obvious from the vulnerability record alone.

If exploitation is suspected, treat credentials and session material on the affected system as potentially exposed. Rotate administrative passwords, API keys, tokens, and any service credentials that the application could access, and verify whether the attacker could have modified content, injected scripts, or persisted through scheduled tasks or planted files.

Risk and Threat Considerations

This CVE is not just a patching issue, it is an active exposure issue whenever the affected Drupal Core version is reachable. Because CISA added it to KEV, attackers have already used it in real attacks, which raises the urgency of exposure confirmation, containment, and compromise review.

Failure mechanism: A remote attacker sends crafted requests that trigger code execution through vulnerable Drupal subsystems, then uses that execution to take control of the application or pivot into reachable resources.

Impact: The result can include full site compromise, data theft, content tampering, credential exposure, and reuse of the compromised host as a launch point for further intrusion.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

MITRE ATT&CK addresses the attack and risk surface, while NIST CSF 2.0, NIST SP 800-53 Rev 5, OWASP ASVS and CIS Controls v8 set the governance and control requirements practitioners need to meet.

Framework Control / Reference Relevance
NIST CSF 2.0 ID.AM-01 — Physical devices and systems within the organization are inventoried Drupal instances must be inventoried to confirm exposure to this KEV-listed CVE
PR.PS-01 — Configurations are managed and enforced through configuration management processes Drupal RCE risk is reduced by hardened, verified configuration and patch enforcement
DE.CM-01 — Networks and network services are monitored to find potential cybersecurity events Web logs and host telemetry are needed to spot exploitation of the Drupal RCE
Recommendation — Inventory every Drupal host and map it to the vulnerable service owners. Enforce secure configuration and patch state across all Drupal deployments. Monitor web, host, and outbound network telemetry for exploitation indicators.
NIST SP 800-53 Rev 5 SI-2 — Flaw Remediation This CVE requires timely flaw remediation and verification of the fix
AU-6 — Audit Record Review, Analysis, and Reporting Post-exploitation review depends on analysing logs for exploit and persistence evidence
IA-5 — Authenticator Management Compromise of Drupal may expose passwords, tokens, or keys that must be rotated
Recommendation — Apply the Drupal vendor fix and verify the vulnerable path is removed. Review logs for exploit attempts, file changes, and suspicious admin actions. Rotate exposed credentials, tokens, and secrets after suspected compromise.
OWASP ASVS V15 — Secure Coding and Architecture Remote code execution reflects a failure of server-side security architecture and input handling
V16 — Security Logging and Error Handling Detection and compromise review rely on application logging and error visibility
Recommendation — Use secure architecture reviews to eliminate code-execution paths in the application layer. Ensure application logs capture suspicious requests and post-exploit activity.
CIS Controls v8 CIS-7 — Continuous Vulnerability Management A KEV-listed Drupal RCE should be found, prioritised, and verified through vulnerability management
Recommendation — Prioritise KEV-listed Drupal assets and confirm remediation is complete.
MITRE ATT&CK T1190 — Exploit Public-Facing Application Drupal Core remote code execution is an exploit of a public-facing application
Recommendation — Map exploit telemetry to T1190 and hunt for follow-on activity after initial access.

Practitioner Guidance

What to watch for: Prioritise internet-facing Drupal instances, especially where ownership is unclear, patch windows are long, or the application has direct access to sensitive data or credentials. The right question is not only whether the site is patched, but whether the host shows any evidence of pre-remediation compromise.

Practitioner note: For KEV-listed web application CVEs, patching alone is not a complete response. Confirm exposure, review logs, and rotate any secrets that the server could have reached before you close the incident.