Cloudflare has released a new rule as part of its Cloudflare Specials Rulesets, to protect our customers against a high-severity vulnerability in vBulletin.

A new zero-day vulnerability was discovered for vBulletin, a proprietary Internet forum software. By exploiting this vulnerability, bad actors could potentially gain privileged access and control to the host servers on which this software runs, through Remote Code Execution (RCE).

Implications of this vulnerability

At Cloudflare, we use three key indicators to understand the severity of a vulnerability 1) how many customers on Cloudflare are running the affected software 2) the Common Vulnerability Scoring System (CVSS) score, and 3) the OWASP Top 10, an open-source security framework.

We assess this vulnerability to be very significant as it has a CVSS score of 9.8/10 and affects 7 out of the 10 key risk areas of the OWASP 2017 Top 10.

Remote Code Execution is considered a type of injection, which provides the capability to potentially launch a catastrophic attack. Through RCE an attacker can gain privileged access to the host server that might be running the unpatched and vulnerable version of this software. With elevated privileges the attacker could perform malicious activities including discovery of additional vulnerabilities in the system, checks for misconfigured file permissions on configuration files and even delete logs to wipe out the possibility of audit trails to their activities.

We also have often observed attackers exploit RCE vulnerabilities to deploy malware on the host, make it part of a DDoS Botnet attack or exfiltrate valuable data stored in the system.

Cloudflare’s continuously learning Firewall has you covered

At Cloudflare, we continuously strive to improve the security posture of our customers by quickly and seamlessly mitigating vulnerabilities of this nature. Protection against common RCE attacks is a standard feature of Cloudflare's Managed Rulesets. To provide coverage for this specific vulnerability, we have deployed a new rule within our Cloudflare Specials Rulesets (ruleId: 100166). Customers who have our Managed Rulesets and Cloudflare Specials enabled will be immediately protected against this vulnerability.

To check whether you have this protection enabled, please login, navigate to the Firewall tab and under the Managed Rulesets tab you will find the toggle to enable the WAF Managed Rulesets. See below:

Next, confirm that you have the Cloudflare Specials Rulesets enabled, by checking in the Managed Rulesets card as shown below:

Our customers who use our free services or those who don't have Cloudflare's Managed Rulesets turned on, can also protect themselves by deploying a patch on their own. The vBulletin team have released a security patch, the details of which can be found here.

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