SB2021042016 - Path traversal in SonicWall Email Security

Description

This security bulletin contains information about 1 security vulnerability.

1) Path traversal (CVE-ID: CVE-2021-20023)

The vulnerability allows a remote user to perform directory traversal attacks.

The vulnerability exists due to input validation error when processing directory traversal sequences within the "branding"  feature. A remote authenticated user can send a specially crafted HTTP request and read arbitrary files on the system with NT AUTHORITY\SYSTEM account.

Request example:

https://<SonicWall ES host>/dload_apps?action=<any value>&path=..%2F..%2F..%2F..%2F..%2Fwindows%2Fsystem32%2Fcalc.exe&id=update

Note, the vulnerability is being actively exploited in the wild.

Remediation

Install update from vendor's website.

References

• https://psirt.global.sonicwall.com/vuln-detail/SNWLID-2021-0010
• https://www.fireeye.com/blog/threat-research/2021/04/zero-day-exploits-in-sonicwall-email-security-lead-to-compromise.html