SB2021020931 - Multiple vulnerabilities in Microsoft Exchange Server

Description

This security bulletin contains information about 2 vulnerabilities.

1) Cross-site request forgery (CVE-ID: CVE-2021-24085)

CWE-ID: CWE-352 - Cross-Site Request Forgery (CSRF)

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L/E:P/U:Green

The vulnerability allows a remote attacker to perform cross-site request forgery attacks.

The vulnerability exists due to insecure generation of CSRF tokens for office-addins installation within the HasValidCanary function inside of the Canary15 class. A remote user can trick the victim to visit a specially crafted web page and escalate privileges on the server.

2) Spoofing attack (CVE-ID: CVE-2021-1730)

CWE-ID: CWE-451 - User Interface (UI) Misrepresentation of Critical Information (Clickjacking, spoofing)

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to incorrect processing of user-supplied data in the Exchange Server Installer. A remote attacker can spoof page content.

Remediation

Install update from vendor's website.

References

• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-24085
• https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-1730