CVE-2019-1921 Explained : Impact and Mitigation

A weakness in the attachment scanning feature of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) allows a remote attacker to bypass content filters without authentication.

Understanding CVE-2019-1921

This CVE involves a vulnerability in the email body input validation of Cisco ESA, enabling attackers to circumvent content filters.

What is CVE-2019-1921?

The vulnerability in Cisco ESA's attachment scanning feature permits attackers to bypass configured content filters by using a specific pattern in a malicious attachment.

The Impact of CVE-2019-1921

CVSS Base Score: 5.8 (Medium Severity)
Attack Vector: Network
Attack Complexity: Low
Integrity Impact: Low
Scope: Changed
Privileges Required: None

Technical Details of CVE-2019-1921

This section provides detailed technical information about the vulnerability.

Vulnerability Description

The vulnerability arises from inadequate validation of input in the email body, allowing attackers to bypass content filters.

Affected Systems and Versions

Affected Product: Cisco Email Security Appliance (ESA)
Affected Version: 12.0.0-419

Exploitation Mechanism

Attackers can exploit this vulnerability by designating a malevolent attachment with a specific pattern, enabling them to bypass content filters.

Mitigation and Prevention

Protect your systems from CVE-2019-1921 with the following steps:

Immediate Steps to Take

Update Cisco ESA to the latest version
Monitor network traffic for any suspicious activity
Implement strong email security protocols

Long-Term Security Practices

Conduct regular security audits and assessments
Train employees on identifying phishing attempts and malicious attachments
Implement a comprehensive cybersecurity policy

Patching and Updates

Apply patches and updates provided by Cisco to address this vulnerability