Zero-day vulnerability in Vigor 2960

Improper Neutralization of Special Elements in Output Used by a Downstream Component
CVE-2020-8515

The vulnerability in WebUI of DrayTek Vigor enterprise routers is being exploited in the wild at least from December 4, 2019. Two affected scripts are believed to be used by two different attack groups to eavesdrop on FTP and email traffic inside corporate networks.

Vulnerability details

Advisory: SB2020021407 - Remote code execution in Draytek Vigor 2960, 3900 and 300B

Vulnerable component: Vigor 2960

CVE-ID: CVE-2020-8515

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

CWE-ID: CWE-74 - Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Description:

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

The vulnerability exists due to the affected devices allow remote code execution as root (without authentication) via shell metacharacters to the "cgi-bin/mainfunction.cgi" URI.

Note, this vulnerability is being actively exploited in the wild starting from December 4, 2019.

Public Exploits:

- Multiple DrayTek Products - Pre-authentication Remote Root Code Execution [Exploit-DB]

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.