Nick Carr Profile picture
Jan 15, 2020 5 tweets 5 min read Read on X
For flowbits in @snort 🐷, order matters:

In Suricata, flowbits:isset is checked after the fast pattern match but before other content matches.

In Snort, flowbits:isset is checked in the order it appears in the rule, from left to right.

Source: suricata.readthedocs.io/en/latest/rule…
@snort I really like using flowbits for exploitation attempts & responses.
I started doing this when tackling those massive #Struts vulns. And today we explained how to use them for CVE-2019-19781: fireeye.com/blog/products-… Image
@snort @_bromiley POP QUIZ: what does this do?
𝗱𝗶𝘀𝘁𝗮𝗻𝗰𝗲:-𝟭;

To see it in action, see our blog post: fireeye.com/blog/products-… (source of screenshot)

The next tweet has the answer. Image
This is distance, @snort's content keyword modifier for how many bytes to begin looking after the previous content match.
I first saw negative distance years ago in my teammate @reesespcres's rules.
Here's a helpful @TalosSecurity blog from 2012 with more: blog.talosintelligence.com/2012/09/using-…
@snort @reesespcres @TalosSecurity Ok if we're going to go all the way back and you somehow haven't read @JoelEsler's 2010 blog on offset + depth and distance + within ... please do so now: blog.joelesler.net/2010/03/offset…

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More from @ItsReallyNick

May 2, 2023
I understand there’s renewed interest in operational timelines re:SolarWinds supply chain compromise attackers

Was proud to publish this one within a week of staying up overnight & discovering how the attackers were persisting with backdoored applications.

Many other methods… twitter.com/i/web/status/1… Image
The value of our (+@cglyer) real-time attacker technique collaboration with absolute beasts in the industry @doughsec 😶‍🌫️, @penninajx + @srunnels 💻 cannot be overstated bringing together puzzle pieces for the RE wizards on each side
From the new @WIRED article: wired.com/story/the-unto…
———
While Mandia conferred with the government, Charles Carmakal, the CTO of Mandiant Consulting, contacted some old friends. Many of the hackers’ tactics were unfamiliar, and he wanted to see whether two former Mandiant… twitter.com/i/web/status/1…
Read 5 tweets
Mar 23, 2022
We've been tracking DEV-0537 since 2021 (overlaps: Lapsus$, UNC3661). Here's a comprehensive 🆕 BLOG 📰 covering observed TTPs: microsoft.com/security/blog/…

#MSTIC and Defender threat intel collab
#DART 👻 incident response team experience from the trenches [1/3]
The blog highlights varied initial access vectors and a slew of [inconsistent?] end goals: data theft, extortion, chaos...

One way to interpret "this actor's TTPs and infrastructure are constantly changing" is that they are loosely-organized (see: ) [2/3]
DEV-0537 / Lapsus$ shows that 𝘢𝘵𝘵𝘢𝘤𝘬𝘦𝘳𝘴 can be creative opportunists and still be successful.
Luckily, the same goes for 𝘥𝘦𝘧𝘦𝘯𝘥𝘦𝘳𝘴.
Use this opportunity to strengthen your security controls to protect far beyond this threat actor [3/3] microsoft.com/security/blog/…
Read 4 tweets
Dec 14, 2020
So you want to talk about the massive software supply chain intrusion & the most carefully-planned, complex espionage I’ve ever helped uncover?

Start here: fireeye.com/blog/threat-re… 🤩

But then what?? Let’s talk about some post-compromise techniques...
Please read the above blog to appreciate multiple backdoors used, careful & unique tradecraft used on-premise...

We just published more details on what we’ve been finding post-compromise: blogs.microsoft.com/on-the-issues/…
ADFS key material compromise, SAML shenanigans, OAuth keys added...
Within the technical companion blog (msrc-blog.microsoft.com/2020/12/13/cus…) we provide some late stage killchain activity observed many places.

I want to highlight the additional detections pushed to cover these techniques in @MSAzureSentinel (but anyone can use on the UAL for #DFIR) ...
Read 9 tweets
Sep 10, 2020
Added #STRONTIUM election-related credential harvesting campaign "detection" to #AzureSentinel: github.com/Azure/Azure-Se…

Yes - it's hardcoded for netblocks released in the #MSTIC report (microsoft.com/security/blog/…)
This is just extra coverage on top of existing cred harvesting logic
That said, the logic posted there finds some high fidelity #STRONTIUM campaigns from at least June through... recently (more details in above blog).

You'll see a User-Agent, first/last attempt, # of total attempts, # of unique IPs & unique accounts attempted + a list of accounts
As shipped, it's looking over the past 30 days. But if you have #AzureSentinel, I recommend pasting that same KQL in & searchings logs w/ expanded timeframe.
The # authAttempts can stay where it's at ... #STRONTIUM activity is approx 100 attempts per IP per account
Read 4 tweets
Sep 10, 2020
Pokéregex Challenge:
How many of the 719 Pokémon can you capture in a single regular expression that fits in a tweet?

Here's what to match: gist.githubusercontent.com/itsreallynick/…

Here are awesome regex resources: raw.githubusercontent.com/aloisdg/awesom… [this same text blob will also be used to measure FPs😊]
If you haven't done something like this before, here's a [crappy] bash one-liner to start:

sh -c 'pattern="your|regex"; echo 🎯 Pokémon:; curl -s gist.githubusercontent.com/itsreallynick/… | grep -ioE $pattern | wc -l; echo 🚯 Noise:; curl -s github.com/aloisdg/awesom… | grep -ioE $pattern | wc -l'
Oh, if it wasn't clear ... you put your regular expression in where it says "your|regex"

Because, as written, the results are pretty terrible 😄 [pictured]

This is similar to an interview question @TekDefense & I would ask @ Mandiant.
It's also an #APT32 hunting tweet. 😉🌶️ This is probably a terrible...
Read 7 tweets
Jul 31, 2020
I started playing Pokémon Go with my kids at the start of the COVID-19 pandemic.

I can’t believe how many #infosec Pokémon we’ve caught so far.

Here’s a quick thread – please add since I’m missing many.

First up: I definitely appreciate that they included #FIN7 in this game Image
That last one was much harder to capture than these Iranian TTP Pokémon. ImageImage
This #infosec Pokémon is an absolute thug. It’s fun every year & a new one is appearing soon #flareon7 Image
Read 8 tweets

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