Explain Cisco ETA to Me in a Way That Even My Neighbor Can Understand It

Cisco Encrypted Traffic Analytics (ETA) sounds just a little bit like magic the first time you hear about it. Cisco is basically proposing that when you turn on ETA, your network can (magically!) detect malicious traffic (ie, malware, trojans, ransomware, etc) inside encrypted flows. Further, Cisco proposes that ETA can differentiate legitimate encrypted traffic from malicious encrypted traffic.

Uhmm, how?

The immediate mental model that springs to mind is that of a web proxy that intercepts HTTP traffic. In order to intercept TLS-encrypted HTTPS traffic, there's a complicated dance that has to happen around building a Certificate Authority, distributing the CA's public certificate to every device that will connect through the proxy and then actually configuring the endpoints and/or network to push the HTTPS traffic to the proxy. This is often referred to as “man-in-the-middle” (MiTM) because the proxy actually breaks into the encrypted session between the client and the server. In the end, the proxy has access to the clear-text communication.

Is ETA using a similar method and breaking into the encrypted session?

In this article, I'm going to use an analogy to describe how ETA does what it does. Afterwards, you should feel more comfortable about how ETA works and not be worried about any magic taking place in your network. ?

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Auto Renew Let's Encrypt Certificates

I'm a big fan of Let's Encrypt (free, widely trusted SSL certificates) but not a big fan of most of the client software available for requesting and renewing certificates. Unlike a typical certificate authority, Let's Encrypt doesn't have a webui for requesting/renewing certs; everything is driven via an automated process that is run between a Let's Encrypt software client and the Let's Encrypt web service.

Since the protocols that Let's Encrypt uses are standards-based, there are many open source clients available. Being security conscious, I have a few concerns with most of the clients:

  • Complication. Many of the clients are hundreds of lines long and unnecessarily complicated. This makes the code really hard to audit and since this code is playing with my crypto key material, I do want to audit it.
  • Elevated privilege. At least one of the clients I saw required root permission. That's a non starter.
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Packets of Interest (2015-06-19)

It's been a while since I've done a POI so here we go. The Mystery of Duqu 2.0: a sophisticated cyberespionage actor returns https://securelist.com/blog/research/70504/the-mystery-of-duqu-2-0-a-sophisticated-cyberespionage-actor-returns/ Kaspersky Lab found this new variant of the Duqu malware in their own network. They wrote a paper based on their analysis of this new malware. It fascinates me how sophisticated these software packages are and how much effort the threat actors put into them. Diffie-Hellman Key Exchange Diffie-Hellman (DH) is the world's first public key crypto system.
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