Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Access Control Rules Bypass Vulnerability

TL;DR 📌

A medium severity vulnerability has been identified in Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Software, allowing unauthenticated remote attackers to bypass access control rules for loopback interfaces. No workarounds are available, and software updates are necessary to mitigate the risk.

What happened 🕵️‍♂️

Cisco has disclosed a vulnerability in the access control rules implementation for loopback interfaces in its Secure Firewall ASA and FTD Software. This flaw could enable an unauthenticated remote attacker to send traffic that should be blocked to a loopback interface, effectively bypassing configured access control rules. The vulnerability arises from improper enforcement of these rules, posing a potential risk to network security.

Affected products 🖥️

The vulnerability affects Cisco Secure Firewall ASA and Secure Firewall FTD Software running vulnerable releases that have at least one loopback interface configured and enabled. Loopback interfaces are not configured by default, so devices without them are not at risk.

Fixed software 🔧

Upgrade to the first fixed release in your train (or later):

Workarounds 🧯

There are no workarounds available to mitigate this vulnerability.

Risk in context 🎯

The highest CVSS score for this vulnerability is 5.3, categorizing it as medium severity. While the risk is not critical, the potential for unauthorized access to loopback interfaces could lead to further exploitation if not addressed. Organizations should prioritize applying the necessary software updates to protect their network infrastructure.

Fast facts ⚡

• Vulnerability: Access Control Rules Bypass
• CVSS Score: 5.3 (Medium)
• Exploitability: Unauthenticated remote access possible
• Workarounds: None available
• Impact: Potential unauthorized access to loopback interfaces

For leadership 🧭

This vulnerability presents a Medium risk to our network infrastructure, with a CVSS score of 5.3. It allows unauthenticated remote attackers to bypass access control rules for loopback interfaces, which could lead to unauthorized access to sensitive areas of our network. Immediate remediation is required—patch within 7 days—to mitigate this risk, as there are no workarounds available. The operational impact involves a brief maintenance window with no expected configuration drift.

Now: Assess and identify affected devices with loopback interfaces.
Next: Schedule and apply the necessary software updates.
Later: Monitor for any signs of exploitation or unusual activity related to this vulnerability.