Filter Bypass in Cisco AsyncOS for Cisco Email Security Appliance

1) Input validation error

EUVDB-ID: #VU25479

Risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-12706

CWE-ID: CWE-20 - Improper input validation

Exploit availability: No

Description

The vulnerability allows a remote attacker to bypass the configured user filters on an affected device.

The vulnerability exists within the Sender Policy Framework (SPF) functionality due to the affected software insufficiently validates certain incoming SPF messages. A remote attacker can send a custom SPF packet to an affected device and bypass the configured header filters, which could allow malicious content to pass through the device.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Cisco AsyncOS for Cisco Email Security Appliance: before 12.5.1

CPE2.3

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

External links

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20191002-esa-bypass

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 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.