246. That's How TinyLoader Maintains Persistence

Hello everyone!

Recently I spotted another persistence technique I don't see to be used by adversaries often. I'm talking about the following technique: Change Default File Association (T1546.001).


According to this report, TinyLoader modified the following registry key to hijack how Windows handles text files:

HKEY_CLASSES_ROOT\txtfile\shell\open\command

This allows the malware to be executed every time a victim opens a .txt file.

So, we can hunt for registry modification events related to this key:

event_type: "registryvaluesetwin"

AND

reg_key_path: "txtfile\\shell\\open\\command"

See you tomorrow!

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