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Remote code execution in Draytek Vigor 2960, 3900 and 300B



Published: 2020-02-14 | Updated: 2020-03-28
Severity Critical
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2020-8515
CWE ID CWE-74
Exploitation vector Network
Public exploit This vulnerability is being exploited in the wild.
Vulnerable software
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Vigor 2960
Hardware solutions / Routers & switches, VoIP, GSM, etc

Vigor 3900
Hardware solutions / Routers & switches, VoIP, GSM, etc

Vigor 300B
Hardware solutions / Routers & switches, VoIP, GSM, etc

Vendor DrayTek Corp.

Security Advisory

Updated: 28.03.2020

Added information about in the wild vulnerability exploitation, raised severity level for this bulletin from high to critical, updated references section and CVSS score.

1) Improper Neutralization of Special Elements in Output Used by a Downstream Component

Severity: Critical

CVSSv3: 8.8 [CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:O/RC:C] [PCI]

CVE-ID: CVE-2020-8515

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

Exploit availability: Yes [Search exploit]

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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Vigor 2960: 1.3.1_Beta

Vigor 3900: 1.4.4_Beta

Vigor 300B: 1.3.3_Beta, 1.4.2.1_Beta, 1.4.4_Beta

CPE External links

https://sku11army.blogspot.com/2020/01/draytek-unauthenticated-rce-in-draytek.html
https://www.draytek.com/about/security-advisory/vigor3900-/-vigor2960-/-vigor300b-router-web-management-page-vulnerability-(cve-2020-8515)/
https://blog.netlab.360.com/two-zero-days-are-targeting-draytek-broadband-cpe-devices-en/

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected device in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.