Backdrop CMS version 1.23.0

Vulnerability Explanation:

Backdrop CMS version 1.23.0 was discovered to contain a stored cross-site scripting (XSS) vulnerability via the Comment .

Attack Vectors:

The attacker must post something on the "comment" and insert the XSS payload at the "comment" input, and pick the Raw HTML Editor in order to exploit the stored XSS. The XSS payload will be launched immediately after save.

Affected:

• http://ip_address/backdrop/comment/reply/id_reply

• POST /backdrop/comment/reply/id_reply

Payload :

• <img src=x onerror=confirm('Grim-The-Ripper-Team-by-SOSECURE-Thailand')>

Tested on:

1. Backdrop CMS version 1.23.0 (https://github.com/backdrop/backdrop/releases/tag/1.23.0)

2. Firefox version 105

Steps to attack:

1. Enter your username and password; the account must have admin privileges.
2. Select some post at the main website.
3. Enter information into the form provided.
4. Enter the XSS payload in the comment field.
5. Choose "Raw HTML" Editor and Save.
6. The XSS payload will run immediately.

Discoverer:

Grim The Ripper Team by SOSECURE Thailand

Medium:

Disclosure Timeline:

• 2022–09–27: Vulnerability discovered.
• 2022–09–27: Vulnerability reported to the MITRE corporation.
• 2022–10–15: CVE has been reserved.
• 2022–10–31: Public disclosure of the vulnerability.

Reference:

3. https://github.com/backdrop/backdrop/releases/tag/1.23.0

4. https://backdropcms.org