John Marrett

John is Stack8's Director of Managed Services. John specializes in network and security, by developing innovative solutions for our clients and providing them with ongoing support.

Recent Posts

Enumerating Cisco ASA systems affected by CVE-2018-0101 using Shodan

Posted by John Marrett on Feb 5, 2018 1:43:57 PM

By now you've almost certainly heard about CVE-2018-0101, an unauthenticated, remote code execution vulnerability affecting Cisco ASAs. If you haven't, you should start planning to apply the update immediately to the ASAs in your environment. This vulnerability affects all ASAs that are configured to handle AnyConnect or clientless VPN connections. Some initial discussion in the security groups suggested that only clientless VPN was affected however this is not the case.

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Topics: CVE-2018-0101, Shodan, ASA

Spectre and Meltdown Update CVE-2017-5753, CVE-2017-5715, CVE-2017-5754

Posted by John Marrett on Jan 22, 2018 11:58:23 AM

Few people would write up a security vulnerability 19 days after it was announced, but in the case of Spectre and Meltdown (CVE-2017-5753, CVE-2017-5715, CVE-2017-5754) each day that we've waited has brought new developments and additional information for us to consider, consolidate and present to our customers and blog community.

Readers who follow security news are already aware that the Spectre and Meltdown issues are substantial threats that have severe impacts on security. The vulnerabilities allow processes to read memory information that should not be accessible to them. User processes can access information from other processes and the kernel, in a virtualized environment they can also access information on the host and potentially other guests.

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Topics: spectre, meltdown, CVE-2017-5753, CVE-2017-5715, CVE-2017-5754

Cisco Router and Google Cloud VPN

Posted by John Marrett on Nov 8, 2017 9:29:02 AM

In a recent consulting engagement, our Professional Services team needed to help build a VPN connection between a series of Cisco Routers and a Google Cloud environment. We were surprised to discover that at the time we completed the project, Google did not provide a configuration guide for this common configuration type and wanted to share our experience building the connection. They have since added documentation for IKEv2 based ASR configurations. Our post highlights some important architectural details as well as the configuration requirements (tunnel mode, phase 2 timers) for the tunnels. It also makes use of an inner VRF, unlike Google's example.

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Topics: Cisco Router, Google Cloud, VPN, GCP

WPA2 Wireless KRACK Attack and Your Network

Posted by John Marrett on Oct 17, 2017 10:10:10 AM

Early yesterday morning a collection of major vulnerabilities in most implementations of WPA2 was made public. The impact of this set of attacks, known as KRACK (Key Reinstallation Attack) is severe, allowing decryption of wireless traffic and, in some cases, traffic modification. You can find out more details on this attack at the website created by the discoverer and in the research paper Key Reinstallation Attacks: Forcing Nonce Reuse in WPA2. Cisco is beginning to release updated firmware for their affected products. You can use this CERT page to find security updates from all the different impacted vendors.

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Topics: WPA2, KRACK

Apache Struts 2, CVE-2017-9805 and Cisco

Posted by John Marrett on Sep 6, 2017 11:37:05 AM

On September 5th a critical vulnerability  affecting the Apache Struts 2 framework was made public with the release of an updated version 2.5.13

There is already publicly available exploit code for metasploit circulating for this vulnerability (be careful if you use this code, we can't vouch for its security and early release exploit code sometimes targets the user). 

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Topics: CVE-2017-9805, CUCM, apache struts

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