Zero-day vulnerability in SonicWall On-premise Email Security (ES)

Arbitrary file upload
CVE-2021-20022

The vulnerability was used in a chained attack to compromise the affected system.

Vulnerability details

Advisory: SB2021041210 - Multiple vulnerabilities in SonicWall On-premise Email Security (ES) and Hosted Email Security (HES)

Vulnerable component: SonicWall On-premise Email Security (ES)

CVE-ID: CVE-2021-20022

CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-434 - Unrestricted Upload of File with Dangerous Type

Description:

The vulnerability allows a remote user to compromise vulnerable system.

The vulnerability exists due to insufficient validation of file during file upload within the branding feature. A remote administrator can upload a malicious ZIP archive to the system to an arbitrary location using directory traversal sequences in the filenames inside the uploaded archive and compromise the affected system.

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

External links:


About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.