MACSec Redux


Good ol’ MACSec.

First, I posted a quick and dirty notes-for-myself, MACSec how-to for Juniper.

Then, I posted a similar MACSec howto for Cisco. So here’s a miscellany of different macsec implementations.

Let’s say you want to run your own router, because your Layer 8 & 9 specialists mandate it, here MACSec on linux.

Here’s a guy who did cisco-switch-to-cisco-switch macsec over an mpls link between a cisco and juniper router (because macsec works at layer 1 and thus you need to fake layer 1 via MLPS). So that’s a thing.

Here’s the Extreme Network’s MACSec implementation:

set macsec port mka enable tg.1.1
set macsec pre-shared-key port tg.1.1 ckn foo cak passphrase bar

HP switches macsec config

Brocade MACSec details and also a Brocade sample config of MACSec.

DNS Fuckery


Cloudflare on how they’re mitigating reflection attacks. The tl;dr: optimized crypto (elliptic curve instead of RSA) for signing DNSSEC, refusing the ANY request and keeping responses with the constraints of a 512-byte UDP packet to mitigate amplification.

Detecting DNS Tunnelling via PacketBeat and Watcher and Elasticsearch

RandomDNS for randomizing use of DNSCrypt


hadoop sleuthkit


This is pretty great:

tl;dr for the impatient: sleuthkit forensic analysis foisted onto a hadoop framework for faster processing of large amounts of data

I haven’t had to use sleuthkit/autopsy in a few years but this is a nice bit of amalgamation.

Cisco MACSec Notes


A while back I did notes for MACSec on Juniper devices and here’s the Cisco equivalent of the 802.1AE (“MAC Sec”) implementation

  1. Your Cisco device needs to be running either an IP Base or IP Services image. MACSec is not happening otherwise.
  2. switch# cts credentials id trustsec password mypassword
  3. en then, conf t, then int Gig1/1 (or whatever)
  4. switch(config-if)# cts man
    % Enabling macsec on Gi1/1 (may take a few seconds)…
    switch(config-if-cts-manual)#no propagate sgt
    switch(config-if-cts-manual)#sap pmk abc123 mode-list gcm-encrypt
    switch(config-if-cts-manual)#no shut

Where abc123 is your shared secret. I believe this is analogous to Juniper’s cak. You can do this to aggregated links (“port-channel” for you Cisco folks) but you have to do it before you aggregate the trunks together into a single logical interface. E.g., do this on Gig1/1 and Gig1/2 and then create int Port-channel1 (channel-group 1 mode on in the interface config)


mode-list options are:

  • gcm-encrypt (authentication and encryption)
  • gmac (auth, no encrypt)
  • null (encapsulation only; no auth, no encryption)



  • to use 802.1x (cts dot1x) as opposed to cts man above, you have to enable 802.1x globally on each device.
  • if you select gcm as the sap mode, you need an additional macsec license from cisco (as well as the ipbase or ipservices image/license). if you select gcm without the license, the interface goes into link-down state.


show cts credentials

show macsec summary

show macsec interface

show authentication sessions interface gigabitethernet1/1


Additional reading:

The actual Cisco doc (this is for a cat4500 but translates well most places) (here’s one for 3750/3560)


Inconvenient Message Detection



Steganography that requires computing effort. Steganography is the idea of hiding data in the unimportant bits of an image. This is an old idea. The new twist is that with ‘Inconvenient Message Detection’ (IMD) that data can only be found if the decoder does an amount of computational work that’s decided by the encoder.

Let’s look at how this solved our problem: If some people use IMD, it makes every image suspect. When a mass-observer wants to see what communication is going on, they must use compute power to check every image. Furthermore, because the compute effort needed to find an image is set by the encoder, it is uncertain to the mass-observer; they never knows for certain if they’ve worked hard enough. By contrast, the intended recipient of a message presumably got the single datum that a message exists in some public image and will put in as much compute effort as is needed to find the data in that single image. Having every image on the internet be a potential carrier of secrets makes the mass observation of communication meta-data expensive and uncertain.

Furthermore, even a individual under direct observation can increase their protection with IMD. An individual may own thousands of images of which only one contains an secret. Until the secret is found by an observer, the individual has plausible denyability of the secret’s existence. The observer may even give up before spending the necessary compute effort to find it. This increases their resistance to coercion. · Grass Mud Horse


The Chinese government is not only being deceitful with IP addresses, they’ve also begun cracking down on a mechanism that lets its citizens avoid the bullshit: VPN. Grass Mud Horse!

This action, combined with the DDoS floods, is beneficial to a government that’s intent on isolating its citizens from the free and open Internet. They make it hard to get a packet out of China, but even if you succeed, it’s likely to be blocked by a server that’s been victim of their DDoS.

On the surface, this seems like a good strategy for creating your own private Internet: a network where no packets can enter the west or leave the east.

via · Grass Mud Horse.

I’ve been seeing a lot of probes in my logs — mostly search engines, but a fair bit that wasn’t — from China. And here you go.

Newly published NSA documents show agency could grab all Skype traffic | Ars Technica


The full capture of voice traffic began in February of 2011 for “Skype in” and “Skype out” calls—calls between a Skype user and a land line or cellphone through a gateway to the public switched telephone network (PSTN), captured through warranted taps into Microsoft’s gateways. But in July of 2011, the NSA added the capability of capturing peer-to-peer Skype communications—meaning that the NSA gained the ability to capture peer-to-peer traffic and decrypt it using keys provided by Microsoft through the PRISM warrant request.

via Newly published NSA documents show agency could grab all Skype traffic | Ars Technica.

Two Dudes Prove How Easy It Is to Hack ATMs for Free Cash


Around 2005, crooks discovered that the default factory-set master passcodes for the Tranax and Trident ATMs were printed right in the service manuals, which were readily available online. Triton’s master passcode was “123456.”

The manuals urged machine owners to immediately change the passcodes from the defaults, but many of the small business owners who favor the inexpensive, pedestal-sized machines never made the change. That led to an uncommon phenomenon in the world of cyber crime: hacking as a street crime.

via Two Dudes Prove How Easy It Is to Hack ATMs for Free Cash | WIRED.


  The tragedy is not that it happened, but that it keeps happening. But: people. Why not set them with a “must change password on first boot” bit? Because lazy people, that’s why.

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An Unprecedented Look at Stuxnet, the World’s First Digital Weapon | WIRED


Don’t run “strings” against files…



Many shell users, and certainly most of the people working in computer forensics or other fields of information security, have a habit of running/usr/bin/strings on binary files originating from the Internet. Their understanding is that the tool simply scans the file for runs of printable characters and dumps them to stdout – something that is very unlikely to put you at any risk.

It is much less known that the Linux version of strings is an integral part of GNU binutils, a suite of tools that specializes in the manipulation of several dozen executable formats using a bundled library called libbfd.

Other well-known utilities in that suite include objdump and readelf.Perhaps simply by the virtue of being a part of that bundle, the strings utility tries to leverage the common libbfd infrastructure to detect supported executable formats and “optimize” the process by extracting text only from specific sections of the file. Unfortunately, the underlying library can be hardly described as safe: a quick pass with afl (and probably with any other competent fuzzer) quickly reveals a range of troubling and likely exploitable out-of-bounds crashes due to very limited range checking

Check the site for POC code. It’s old and it’s nasty.

Categories : Security