Traffic filtering allows for it and a powerful and customizable way to do that is with Access Control Lists.īut what about when you need someone on the outside to be able to come in and do things on the inside? Or what if you want to stop someone on the inside from accessing specific outside resources? Fortunately, it's possible to instruct your ASA about which traffic is permissible.
With a Cisco Adaptive Security Appliance set up on your network, by default, a low-security interface - like a so-called "outside" interface at Level 0 - can't go in and access resources on a high-security interface - like an "inside" interface at level 100. In no time at all we could very well be seeing Shai-Hulud wormsign the likes of which we have not seen before.Watch now When Would You Need Traffic Filtering?Īnytime you want to permit someone on the outside of your protected network access something on the inside, or prevent someone on the inside from accessing specific resources on the outside, you need traffic filtering. You need to start patching as soon as possible as I can well imagine that this will get worse before it gets better. If you are working for an organization that fins you responsible for the oversight of ASA firewalls and you've made it this far into the post, stop. So, what products are feeling the pressure of this problem? Well, here is a list gleaned from the Cisco Advisory. The Cisco ASA Software running on the following products may be affected by this vulnerability:Ĭisco ASA 5500 Series Adaptive Security Appliances Cisco ASA 5500-X Series Next-Generation Firewalls Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers Cisco ASA 1000V Cloud Firewall Cisco Adaptive Security Virtual Appliance (ASAv) Cisco Firepower 9300 ASA Security Module Cisco ISA 3000 Industrial Security Appliance So, how did this make it past QA? A question that I'm certain someone will be wanting an answer for. Attackers can use this vulnerability to execute arbitrary code on affected devices. A sequence of payloads with carefully chosen parameters causes a buffer of insufficient size to be allocated in the heap which is then overflowed when fragment payloads are copied into the buffer. The algorithm for re-assembling IKE payloads fragmented with the Cisco fragmentation protocol contains a bounds-checking flaw that allows a heap buffer to be overflowed with attacker-controlled data.
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