MitM atack in Cisco Email Security Appliance and Cisco Web Security Appliance

1) Improper Certificate Validation

EUVDB-ID: #VU54172

Risk: Medium

CVSSv3.1: 5.5 [CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-1566

CWE-ID: CWE-295 - Improper Certificate Validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to preform MitM attack.

The vulnerability exists due to improper certificate validation when establishing TLS connection. A remote attacker can perform a man-in-the-middle (MitM) attack.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Cisco AsyncOS for Web Security Appliances: before 11.8.3 021

Cisco AsyncOS for Cisco Email Security Appliance: before 12.5.3 035

CPE2.3

• cpe:2.3:a:cisco_systems:cisco_asyncos_for_web_security_appliances:*:*:*:*:*:*:*:
• cpe:2.3:a:cisco_systems:cisco_asyncos_for_cisco_email_security_appliance:*:*:*:*:*:*:*:

External links

http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-wsa-cert-vali-n8L97RW
http://bst.cloudapps.cisco.com/bugsearch/bug/CSCvw08342
http://bst.cloudapps.cisco.com/bugsearch/bug/CSCvw08378

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the local network (LAN).

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.