CVE-2019-1905 : What You Need to Know

Cisco Email Security Appliance GZIP Content Filter Bypass Vulnerability

Understanding CVE-2019-1905

This CVE involves a vulnerability in the GZIP decompression engine of Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) that could allow an unauthorized attacker to bypass content filters on the device.

What is CVE-2019-1905?

The flaw in the GZIP decompression engine of Cisco ESA could be exploited by an attacker to circumvent content filters, enabling the attacker to send malicious files that would typically be blocked.

The Impact of CVE-2019-1905

The vulnerability could lead to a bypass of content filters, potentially allowing malicious files to pass through undetected, compromising the security of the email system.

Technical Details of CVE-2019-1905

The following are the technical details of this CVE:

Vulnerability Description

The vulnerability arises from inadequate validation of GZIP-formatted files, allowing attackers to send specially crafted GZIP-compressed files containing malicious content.

Affected Systems and Versions

Product: Cisco Email Security Appliance (ESA)
Vendor: Cisco
Version: 12.0

Exploitation Mechanism

Attack Complexity: Low
Attack Vector: Network
Privileges Required: None
User Interaction: None
Scope: Changed
CVSS Base Score: 5.8 (Medium Severity)
Vector String: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Mitigation and Prevention

Steps to address and prevent exploitation of CVE-2019-1905:

Immediate Steps to Take

Apply vendor-provided patches and updates promptly.
Monitor vendor communications for security advisories.
Implement network segmentation to limit the impact of potential attacks.

Long-Term Security Practices

Regularly update and patch all software and systems.
Conduct security training for employees to recognize and report suspicious emails.
Implement multi-layered security measures to detect and prevent email threats.

Patching and Updates

Cisco has released patches to address this vulnerability. Ensure timely application of these patches to secure the affected systems.