Vulnerability identifier: #VU9658

Vulnerability risk: High

CVSSv3.1: 9 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H/E:P/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-94

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
vBulletin
Web applications / Forum & blogging software

Vendor: vBulletin

Description
The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The weakness exists in vBulletin installations on Windows OS due to the file inclusion vulnerability with parameter "routestring". A remote unauthenticated attacker can send a GET request to /index.php, inject malicious PHP code into a file on the server (e.g. access.log), “include” that file in the request and execute arbitrary PHP code.

Successful exploitation of the vulnerability may result in system compromise.

Mitigation
Install update from vendor's website.

Vulnerable software versions

vBulletin: 5.3.0 - 5.3.4

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External links
http://blogs.securiteam.com/index.php/archives/3569
http://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4383554-security-patch-released-for-vbulletin-5-3-2-5-3-3-and-5-3-4

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.