Drupal RCE Vulnerability Requires Immediate Patching

A remote code execution vulnerability in several versions of Drupal's content management platform requires immediate patching by users. For its part, Drupal is getting out in front of this problem.

Larry Loeb, Blogger, Informationweek

April 2, 2018

3 Min Read

Drupal, the widely popular content management system for websites, has been found to have a "highly critical" remote code execution (RCE) vulnerability that requires immediate patching.

The vulnerability (CVE-2018-7600) could allow complete takeover of the affected site from "multiple attack vectors," according to the Drupal team. It has a risk score of 21/25.

The result of the problem is that any visitor, no matter what privileges that they have been assigned, can gain access to, modify and delete private data.

(Source: Flickr)

(Source: Flickr)

According to Drupal, the RCE affects the Bootstrap system. The file that needs patching is located in /apps/drupalhome/includes/bootstrap.inc. The developer team also notes that the vulnerability is activated through either maliciously formed cookies, POST requests or query strings. That would mean that the maintenance page or the user/login may also be vulnerable. So, simply turning the site maintenance mode active will not work since that module uses Bootstrap.

It seems that the vulnerability lies within the logic of Drupal's PHP code -- in that it does not allow for necessary input validation.

Drupal has written in a FAQ section that this RCE problem is not currently active in the wild. However, engineers do expect attackers to develop exploits very soon after the announcement, hence their advice to immediately upgrade or patch.

The problem affects versions 6,7, and 8. Version 7.58 and 8.51 are the latest Drupal versions, and are deemed by Drupal not to have the RCE problem. Since Drupal 6 is on end-of-life status, Drupal recommends contacting the long-term D6 vendors for support and patches.

Patches are also available if immediate upgrading cannot be accomplished, but Drupal does recommend that their use only be temporary until a full upgrade can be performed.

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If patching cannot be done immediately, Drupal points to other mitigation methods.

These methods are all based on the idea of not serving vulnerable Drupal pages to visitors. According to Drupal:

"Temporarily replacing your Drupal site with a static HTML (ed. -- static here means an invariant page with no database accessing performed) page is an effective mitigation. For staging or development sites you could disable the site or turn on a "Basic Auth" password to prevent access to the site."

Cloudflare has pushed out a Drupal Web Application Firewall Rule to address the exploit. This doesn't directly help Nginx or Apache users, however.

The Drupal response to the RCE is seemingly exactly what one would want to happen. The team acted responsibly by not hiding it or downplaying it, and have provided a wide range of ways to mediate the problem.

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— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

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About the Author(s)

Larry Loeb

Blogger, Informationweek

Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek. He has written a book on the Secure Electronic Transaction Internet protocol. His latest book has the commercially obligatory title of Hack Proofing XML. He's been online since uucp "bang" addressing (where the world existed relative to !decvax), serving as editor of the Macintosh Exchange on BIX and the VARBusiness Exchange. His first Mac had 128 KB of memory, which was a big step up from his first 1130, which had 4 KB, as did his first 1401. You can e-mail him at [email protected].

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