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Hello and good evening on day two of the chaos communication Camp 2023 Translated by {Yang}{Li} (ITKST56 course assignment at JYU.FI)]

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it's late in the evening this is meleeway stage in case you're wondering

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and the next talk is going to be about incident report responses

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so if you're curious about how to even get there to have an incident response how you could [br]prepare for an incident response and how you could support a new organization

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uh, the incident response team in doing the job and trying to fix whatever broke

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let's put it that way um we have the right talk for you

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this is stories from the life of an incident from incident responders Harry and Chris

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please a very warm Round of Applause [Applause]

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so, good evening and thank you for joining us today um we will tell you a little bit of our

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life as incident responders and I'm Chris I did my computer science

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studies at the University of alang and Nuremberg I do this security stuff for

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over 10 years now so my CV is a little bit longer at the moment I'm a detection

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engineer before that I was a long time working in dfir so digital forensic incident

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response in different organizations and

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yeah I'm Harryr I studied electrical and computer engineering at RWTH

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University and I played a lot of CTF and did some hacking stuff at chaos computer club RWTH

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during my masters I worked at x41 dsac doing pen testing patch analysis

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so I also have some kind of offensive security background on for around one year now I'm working at G data Advanced

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analytics doing digital forensics and incident handling

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first Christian will give you a short introduction and then he will tell you how a classical ransomware attack looks

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like and in the second part of the talk I will tell you how the incident

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responders work and what you can do in advance to make it go as smooth as possible and support the incident

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response team so as Harryr told you I will probably

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we'll talk about ransomware because the customers we usually have are small and

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medium-sized businesses universities and hospitals and those are regularly

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unfortunately regularly hit by um um

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ransomware gangs the main reason for this and that's if you heard the last

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talk um why they maybe not that responsive

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and are not so interested in they just lack the resources so the manpower to do

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uh proper security measurements to secure their systems especially in in erm

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situations where you are for example in a hospital have medical devices

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um which where you cannot simply install an AV on or even patch the system

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because you lose the certification as a medical device then but also in in

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companies manufacturing companies on the shop floor we're talking about systems[br]

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that have run times of 25 plus years so if you look back now 2023

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we're talking about XP and older systems fun fact I was in a ransomware case and

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Wannacry in 2017 when I got a call from from a person from the shop floor

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asking me if we have a nt4 expert, um

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that can tell us if WannaCry is affecting nt4 of course you don't need

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to be a expert for NT-4 this one requires of course not affecting nt4

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systems so due to the time uh slot we thought

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memes are the best way to to tell you those stories and we have a lot of them

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so in the first uh um section I tell you a little bit of how an attack Works

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um there are a lot of different possibilities how you can describe and how to structure the how an attack works

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there's the miter attack framework for example there was for example a talk Yesterday by Maker Salko

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um here on the stage there's the original cyber kill chain from from Lockheed Martin you have

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stuff from from companies like Mandy and their targeted the tech life cycle but

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that's all in my opinion two two fine-grained it's that's the reason I

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just take three simple steps yeah get a foothold in the door

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look move play around and cash out those three uh I will just go over

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so start with uh get a foot in the door so normally we

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see three ways how attackers can can get into the environment in the ransomware

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cases you have vulnerabilities in uh remote uh internet facing systems you

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have the remote Services itself and you have malware

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starting with the with the the vulnerabilities and um I just looked uh up the last four

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years and maybe somebody remembers netscaler the the so-called Citrix

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vulnerability in December 2019 um it was released mid of uh 2019 uh

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December 2019 the first POC publicly available POC was in beginning of

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January and the patch was available in middle of January so there was a round one week to one and a half weeks between

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a public proof of concept for the vulnerability and uh patch for the vulnerability and what we saw

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during 2020 a lot of companies patched but the patch didn't remove the the

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compromise so they were already compromised and um yeah with it with the patch they

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didn't remove the compromise so what we found what we could provable

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see or proof evidence for uh was nine

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month uh customer was breached after nine months using this this vulnerability

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and we had other customers where we could see that the netscaler was affected after two years but we couldn't

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prove that this this compromise was the reason for the actual ransomware case

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and of course such vulnerabilities happen not that often

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yeah so 2021 gave us uh hafnium exchange

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vulnerability also a similar situation the patch

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appeared as an out-of-band patch from Microsoft on a Tuesday evening 10 o'clock in German time

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we saw during our uh incidents or the the assessments we did that

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um the first exploit exploitation attempts were seen on Wednesday in the morning at

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5:00 am so around seven eight hours later um I know one guy who could patch

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because he was online when the patch was released otherwise Germany was unable to patch in

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time and of course we can go on with 2021 proxy shell also

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exchange vulnerability proxy nutshell also exchange vulnerability

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we have uh in 2022 VMware Horizon the the virtual desktop infrastructure

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from VMware just to name also open source stuff Zimbra a collaboration platform

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including an email server uh has had a vulnerability actually the vulnerability

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was in cpio from 2015 I think which led

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to a compromise using via email so you send an email

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with a cpio with a specially crafted archive file and you could drop a web

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shell in one of the directories yeah you have of course 40 OS which is a

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40 gate VPN and firewall operating system

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and if you read the news we start at the beginning again

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netscaler had some issues several weeks ago according to foxIT we have 1900

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still unpatched net scalers worldwide how many patched

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was netscale has exists that um have not been checked for compromise we

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don't know of course so that will be a nice year probably

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um so what can you can you do against this kind of of attack vector patch your systems is one thing as you

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see this that doesn't lead to the the um or what you need to do afterwards in

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such cases you need to check your systems for possible compromise

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that is important to reduce this I highly suggest put your

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uh Services behind some VPN so that only people who already have

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connection to the VPN um can access your services or the services

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they need and that would reduce the attack surface

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at least to the VPN server so but I

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of course we can also think about remote services without vulnerabilities

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um there can be configuration mistakes so the admin does something wrong there can

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be insecure default configurations like this um I don't know if you know it but the

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local admins or the administrators on the Windows system are are

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automatically in the remote desktop users group you know and so

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we had several cases especially in the beginning of the pandemic when everybody moved from uh to the home offices and

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they needed to put people fast in the position to to access their the assist

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the internal systems again they just put a RDP server on the internet and hope for the best

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um additionally if you put services on the internet of course brute forcing and

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credential uh stuffing are attacks that are possible so brute forcing just trying the the

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username and password combinations uh credential stuffing using already leaked

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passwords or credentials from leaks you find on the internet

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what you can do about this kind of of attack Vector is uh just as I said use

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multi-factor Authentication and reduce the attack surface as in the

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point with the vulnerabilities before by moving the services behind a VPN and

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then use multi-factor authentication on VPN of course

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the last Vector that we see normally that the attackers can get in the

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network is malware we all know this about

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those funny emails you get with the attachments

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um include that have either Word documents

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attached either zip files with with Visual Basic scripts javascripts and

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what you can get isos you see a lot these days

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um or what you can also have that you can have just a link inside the email and

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you download the respective file from some some shady file sharing website

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um what we saw over the last year was uh USB sticks again funnily

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um I'm not sure if you have heard about raspberry Robin which is a malware that

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warms via USB sticks um but I haven't seen it as a vector for

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ransomware yet on my own but there are people who said that it's

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an initial access broker for some of the ransomware gangs

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so what can you do about this if you think the

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you can of course ban simply some file extensions in your mail server or you

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change the file Association types in your operating system meaning that you

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don't open the JavaScript and Visual Basic script files using for example the

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windows scripting host but open it with notepad and that will

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of course some people will be

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uh some people will think about what this this is then and ask the IT guys

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but it's better than running the the script itself

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one thing I I I don't like to to say it but keep your AV updated

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um uh this is one thing keep it updated and read the logs

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we see a lot of incidents where we see that the already

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days or weeks before we you can could have seen that there's something going

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on in your network yeah and if you see malware in your AV logs

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then react to it just check it you don't know how long this AV this malware has

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been on your system the thing is that

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just because you're AV detected it now it might have been get received an

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update for its signatures and the malware was active for days or weeks

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before so when they are inside

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then they usually look move and play around a little bit

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so when they look around what they do

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is they they enumerate AD they do Ports scan the you they search for

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vulnerabilities they check uh what they how they can escalate

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their privileges they try to find credentials

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um Kerber roasting we heard in the talk before for example is this one thing

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um they try to identify accounts you around

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have running on your systems they can use they can get the credentials from and you reuse

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and for that reason one of the most important things I think is that you

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have a principle of least privileges in your environment so only what a account needs

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you should be able to do you should use dedicated service

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accounts for your services of course and just for your information

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um service account is not an account that has a SVC underscore in front of it

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and is otherwise a normal user account um there I exist educated service

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accounts in Windows environments so use them use strong passwords I still

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I today I can I know companies who still use eight

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character long passwords um I think that's 20 minutes on a decent

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graphics card today so use strong passwords length matters

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12 plus characters is the minimum in my opinion

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and don't reuse passwords especially on your

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systems the local administrator especially in small and medium-sized businesses you see a lot that people use

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the same password for all local administrators so if I have it on one

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system I have the whole company don't reuse it

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um yeah [Audience LoL]

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so when they they move around in your network using either a password hashes they found valid credentials they they

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discovered somewhere vulnerabilities are also used to to move around in your

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environment they try to to establish persistence mechanisms here we heard

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also in the talk before about the C2 channels command and control channels they use

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um they install in some cases directly any desk team viewer and or other remote

0:19:36.132,0:19:43.572
control software or sometimes they also use tunneling softwares like ngrok or recently they

0:19:43.572,0:19:49.744
started using cloudflare G um and this is what you need to do is

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prop have a proper Network segmentation and with the proper Network segmentation I don't talk about subnetting

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subnetting means you just have different subnets you need to have a firewall between them

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and you have need to have rules between them that

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restrict access between your your subnets and one thing is especially important

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please keep or use Network segmentation to

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restrict the access to your backup and your Management Systems as far as

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possible we see a lot especially as I said in the small and medium-sized businesses or in

0:20:36.197,0:20:40.183
the other organizations we we have as customers that

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yeah they have they tell us in in in in in in workshops yeah we have

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a network segmentation every building is one segment and on the question yeah you

0:20:54.333,0:20:59.603
can move between in a segment you can access everything yes you can and

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between the the buildings you can have also a firewall and you cannot access

0:21:05.911,0:21:11.930
anything no you can access everything and also your your uh VMware Management

0:21:11.930,0:21:17.420
console oh yes yes we can so everybody can access it yes of course and that

0:21:17.461,0:21:21.761
doesn't work so

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um when they play around they normally try

0:21:30.263,0:21:38.288
to to gain more privileges so privilege escalation is assisting local privilege escalations normally but also using

0:21:38.288,0:21:43.440
vulnerabilities um or misconfigurations insecure default

0:21:43.440,0:21:48.981
configurations um my personal favorites are Group

0:21:48.981,0:21:53.211
Policy preferences or passwords in group policy preferences

0:21:54.686,0:22:01.890
this is no longer possible since I think 2014 to put passwords in group policy

0:22:01.890,0:22:07.994
preferences however if you had your password stored in those preferences

0:22:07.994,0:22:16.161
before the patch in 2015 2014 then they're still there and yeah there

0:22:16.161,0:22:20.932
are AES encrypted but the encryption key is on the Microsoft website

0:22:21.783,0:22:26.663
so you can just download it and just take it and decrypt the keys

0:22:28.834,0:22:33.484
um then during that phase they also try to disable your security measures

0:22:34.914,0:22:41.516
the thing you can do is of course patch your system so you know try to get your

0:22:41.516,0:22:46.655
availabilities out of of this equation can try to configure your systems in a

0:22:46.655,0:22:52.580
secure way this is not always possible due to some shitty uh third-party software

0:22:52.897,0:22:58.777
and keep your AV um updated and please please as I said

0:22:58.777,0:23:02.894
already check the locks and act accordingly

0:23:05.511,0:23:09.741
so in the last phase they cash out that's when when they

0:23:10.707,0:23:16.881
start using a uh being your backup service so they copy

0:23:16.881,0:23:21.906
data from your your environment using um

0:23:21.906,0:23:27.574
file sharing platforms for example yeah Mega and set was was once the thing we

0:23:27.574,0:23:33.155
transfer we had already uh every every other file sharing platform you you can

0:23:33.155,0:23:38.891
think about is a possible way to exfiltrate data they also use their

0:23:38.891,0:23:47.270
their C2 communication channels so sometimes you they also they just use the the possibilities in any desk or in

0:23:47.270,0:23:53.014
in RDP clients or they use uh file transfer protocols

0:23:53.014,0:23:57.014
like um SS SFTP um

0:23:59.670,0:24:06.260
we saw for example in one case that they try to install filezilla on every machine they had access to

0:24:06.260,0:24:11.705
um because on the first one it didn't work on the second it didn't work on the third it didn't work yet because SFTP

0:24:11.705,0:24:17.940
was blocked uh outgoing and that is one of the things you can do to to prevent

0:24:17.940,0:24:21.765
exfiltration block at least

0:24:24.607,0:24:30.456
protocols you know that you don't need in your environment and proper Network segmentation of

0:24:30.456,0:24:39.024
course is a general thing so in the last step that's when they

0:24:39.024,0:24:44.781
start the encryption um they're running the ransomware or

0:24:44.781,0:24:50.171
normally they are have domain admins at that point so they can run it on all

0:24:50.171,0:24:57.284
domain connected systems they can also disable of course when they are domain admin they can disable

0:24:57.461,0:25:04.553
the AV before they they start to run somewhere ransomware's today disable services like

0:25:04.553,0:25:10.303
databases and such things so that they have the full power of the machine for

0:25:10.303,0:25:14.590
the uh for the encryption

0:25:15.899,0:25:23.001
um if you get lucky not how everything works perfectly because they use

0:25:23.001,0:25:29.327
group names and windows is especially picky when you have a non-english uh

0:25:32.344,0:25:39.434
windows installed for example in Germany the the group everybody is called yida

0:25:40.319,0:25:47.322
and we had cases where the ransomware didn't really work that well because they couldn't

0:25:47.322,0:25:51.322
change the permissions of the files first um

0:25:53.436,0:25:59.278
they use different encryption schemas normally they they come with the

0:25:59.278,0:26:05.740
asymmetric and the symmetric encryption type the asymmetrics or public key cryptography the public key comes with

0:26:05.740,0:26:12.254
the ransomware and is used to encrypt the symmetric keys they generate on in

0:26:12.254,0:26:20.112
your environment depending on the ransomware they they generate one key for each system or even one key for each

0:26:20.112,0:26:25.876
file it depends a little bit on the on the ransomware how it works but that's

0:26:25.876,0:26:32.998
the usual thing they use um I would never count on the the fact

0:26:32.998,0:26:39.521
that there are possibly maybe there could be

0:26:39.521,0:26:47.544
decryptable uh things um in in my opinion in my uh in my world

0:26:49.120,0:26:55.200
The ransomware Gangs have learned and used the standard Microsoft Windows or

0:26:55.200,0:26:59.232
some other publicly available libraries to to do the encryption

0:27:00.770,0:27:09.224
they executed by a remote tools like PSX Powershell or some use

0:27:09.224,0:27:14.983
gpos group policies to execute the ransomware on every

0:27:14.983,0:27:21.153
machines they they connected to the domain and what can you do about this no it's

0:27:21.153,0:27:26.533
it's hard but the the most important thing is have online backups offline

0:27:26.533,0:27:33.817
backup sorry thanks you you see you see off online backups

0:27:33.817,0:27:39.414
are not that are great but not that great offline backups is the most important this is the most important

0:27:39.414,0:27:45.388
thing so um don't have it connected to your environment

0:27:45.969,0:27:52.207
the the the USB disk on the system is not offline backup

0:27:55.594,0:28:00.794
um in my opinion if you see that something is is still encrypting

0:28:01.440,0:28:07.630
I I'm I'm always hesitant to say shut down the system because you can break

0:28:07.630,0:28:15.529
the encryption and maybe the file that is currently in under encryption or the files will never be decryptable if you

0:28:15.529,0:28:23.588
want to buy a decrypter um or gather the cryptos through some

0:28:25.669,0:28:32.149
discussions with the with the ransomware guys um if it's a VM just suspend it and

0:28:32.149,0:28:38.351
that's it and if everything is already encrypted

0:28:39.205,0:28:43.575
keep cool and call your incident responder

0:28:51.306,0:28:58.606
so now let's talk about incident response what happens when it's already too late and what can you do to support

0:28:58.606,0:29:04.110
your incident response team at first the things I'll say in this chapter are

0:29:04.110,0:29:10.549
for our company and how we work so other companies might work a little bit different than that

0:29:12.792,0:29:17.022
first for some reason incidents always come on Friday afternoon

0:29:18.950,0:29:23.950
so some customers think it is a good idea to try to solve a case by

0:29:23.950,0:29:30.785
themselves maybe until the end of the week and if they didn't solve it until the end of the week they call the

0:29:30.785,0:29:35.876
incident response team please don't do that it doesn't help your company and it

0:29:35.876,0:29:43.792
doesn't make your incident Response Team happy to have to work on the weekend and in addition the longer you wait with

0:29:43.792,0:29:50.859
calling the incident Response Team the longer the incident response will take and the more complicated forensics will

0:29:50.859,0:29:56.523
be because you have lock retention times while trying to do stuff by yourself

0:29:56.702,0:30:01.572
maybe you modify some of the systems and it becomes much more harder to do

0:30:02.397,0:30:08.127
precise forensics so what happens on our site when such a