Path traversal in SonicWall Email Security

1) Path traversal

EUVDB-ID: #VU52377

Risk: High

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:N/E:H/RL:O/RC:C]

CVE-ID: CVE-2021-20023

CWE-ID: CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Exploit availability: No

Description

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.

Mitigation

Install update from vendor's website.

Vulnerable software versions

SonicWall On-premise Email Security (ES): before 10.0.9.6173

SonicWall Hosted Email Security (HES): before 10.0.9.6173

CPE2.3

• cpe:2.3:a:sonicwall:sonicwall_on-premise_email_security_es:*:*:*:*:*:*:*:
• cpe:2.3:a:sonicwall:sonicwall_hosted_email_security_hes:*:*:*:*:*:*:*:

External links

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

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated privileged user via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.