373. Adversaries Keep Abusing Legitimate Cloud Infrastructure, But You Can Hunt For It!

Hello everyone!

The abuse of legitimate cloud services keeps appearing in public cyber threat research reports, so today we’ll look at a couple of examples related both to malware distribution and data exfiltration.

So, the first example we’ll look at is a loader from this report. In this case, the attackers abuse PowerShell to download an image containing malicious code from cloudinary[.]com:

hxxps://res[.]cloudinary[.]com/dbjtzqp4q/image/upload/v1767455040/optimized_MSI_lpsd9p.jpg

In this case, we can search for suspicious PowerShell interactions with cloudinary[.]com:

event_type: "dnsreqwin"

AND

dns_rname: "cloudinary.com"

AND

proc_file_path: "powershell.exe"

Another example is Muddled Libra. The attackers attempted to use several legitimate services for data exfiltration:

upload[.]ee
uploadnow[.]io
filetransfer[.]io
filebin[.]io

Suspicious communications with these services can also be searched for:

event_type: "dnsreq"

AND

dns_rname: ("upload.ee" OR "uploadnow.io" OR "filetransfer.io" OR "filebin.io")

If such services are not needed, they can always be blocked. While attackers may find alternatives for exfiltration, in the case of malware delivery the chain will simply be broken.

See you soon!

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