Privilege escalation in Microsoft SQL Server

1) Input validation error

EUVDB-ID: #VU49489

Risk: Medium

CVSSv4.0: 6.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-1636

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote user to escalate privileges on the system.

The vulnerability exists due to insufficient validation of user-supplied input, when the affected SQL Server is configured to run an Extended Event session. A remote user can send specially crafted data to the server and execute arbitrary code with elevated privileges.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Microsoft SQL Server: 2012 11.0.2100.60 - 2019 15.0.2000.5

CPE2.3

• cpe:2.3:a:microsoft:microsoft_sql_server:2012:11.0.2100.60:*:*:*:*:*:*
• cpe:2.3:a:microsoft:microsoft_sql_server:2014:12.0.2000.8:*:*:*:*:*:*
• cpe:2.3:a:microsoft:microsoft_sql_server:2016:13.0.1601.5:*:*:*:*:*:*
• cpe:2.3:a:microsoft:microsoft_sql_server:2017:14.0.1000.169:*:*:*:*:*:*
• cpe:2.3:a:microsoft:microsoft_sql_server:2019:15.0.2000.5:*:*:*:*:*:*

External links

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1636

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

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

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.