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Sextortion Scam Now With Malicious Downloader

Sextortion scams were a hit campaign last year and are continuing in  2019 with a new trick – the inclusion of an archive attachment which contains a malicious JavaScript downloader as “proof”.

 

Compared to previous spams, the email body contains just a small snippet of the sextortion – a claim that the sender hacked and had access to the recipients’ photos, videos, contacts, and camera recordings. To make it more believable, the attackers attached an archive which serves as “proof” to their claim.

The samples below are in Italian, we translated parts of them for clarity.

Email_zip_translation
Figure 1: Sextortion email sample where the attachment is a password protected ZIP
 
Email_ace
Figure 2: Sextortion email sample where the attachment is an ACE archive which does not require a password

 

The attached archive contains two files – a PDF file “personalmente.pdf” and a JavaScript file “prove_12.js”.

The PDF file “personalmente.pdf” contains the details of the sextortion. The text of the ruse suggests that through malware installed on the recipient’s computer, the hackers were able to gain access to data, and, that the recipient should pay bitcoins to the sender to not release the captured video.

Pdf
Figure 3: The PDF file “personalmente.pdf” inside the attached archive

 

 

The second file in the archive is an obfuscated JavaScript. This file will silently run a PowerShell command to download an executable file, save it to the temp folder, and execute it.

Prove_js_1
Figure 4: The obfuscated JavaScript file “prove_12.js”

The PowerShell command is split into an unordered array. A gibberish string is inserted in between some of the characters to make the split command more unreadable. The JavaScript has its own deobfuscation routine to fix the PowerShell command.

Prove_js_obfuscation
Figure 5: The deobfuscation routine of the JavaScript file “prove_12.js”
 
Ps_code
Figure 6: The PowerShell command from the JavaScript “prove_12.js” will download hxxp://link[.]chillgro[.]com/status[.]exe then save and execute it as %temp%\bAF37.exe


The content at the download URL is no longer accessible as of this writing.

The wider news here is that sextortion is a big thing right now, with several groups behind different campaigns. This one takes it a step further and includes a malware that serves as a door for other malware to be installed in the computer. If you happen to get one in your inbox, ignore it, and chances of it being real are remote.

 

IOC

personalmente.pdf (137332 bytes)
SHA1: 5F851EA45C463F0ADD46F79D998B0EDC5AF71B34

prove_12.js (8011 bytes)
SHA1: BD90191B49B93FB4F1D2FC47D320E04466DFC4A0

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