Padding oracle in cookie encryption in FortiOS

1) Improper Verification of Cryptographic Signature

EUVDB-ID: #VU72346

Risk: Low

CVSSv3.1: 3.8 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-43074

CWE-ID: CWE-347 - Improper Verification of Cryptographic Signature

Exploit availability: No

Description

The vulnerability allows a remote user to gain access to sensitive information.

The vulnerability exists due to improper verification of cryptographic signature when handling cookie files. A remote user can decrypt portions of the administrative session management cookie (padding oracle in cookie encryption) and escalate privileges on the device.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

FortiOS: 6.0.0 - 7.0.6

External links

http://fortiguard.com/psirt/FG-IR-21-126

Q & A

Can this vulnerability be exploited remotely?

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

Is there known malware, which exploits this vulnerability?

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