Password Protected Word Document Delivers HERMES Ransomware

Evading AV detection is part of a malware author's routine in crafting spam campaigns and an old and effective way of achieving this is spamming a password protected document. Recently, we observed such a password protected document being spammed out, and even worse, its payload was ransomware.

 

Email_sample
Figure 1: Email sample containing the password for the attachment "Invoice.doc"

 

Doc_pwd
Figure 2: User is required to input the password to open the document

 

The "Invoice.doc" attachment contains a macro. If the user's macro security setting is Low, the document will automatically launch the macro. Furthermore, the macro is password protected. Unfortunately, faced with this, most users will not have any idea what this document will do on the background.

Looking at the content of the macro reveals it will download a file from hxxp://209[.]141[.]59[.]124/azo.exe, then save and launch it as %temp%\qwerty2.exe. Eventually from on the same IP address, this azo.exe will download and execute hrms.exe which is the HERMES 2.1 Ransomware.

Macro_azo
Figure 3: Macro inside the "Invoice.doc" attachment

 

The Hermes 2.1 Ransomware does not add its own file extension to the encrypted files. Once the infection is over, it will launch DECRYPT_INFORMATION.html from the user's desktop.

Hermes_2
Figure 4: Hermes 2.1 Ransomware DECRYPT_INFORMATION.html
Hermes
Figure 5: Enabling ActiveX will show the Ransomware Note

 

Interestingly, at around the same time, we also observed an email sample with same the subject and almost identical email headers and body. However, the attachment was a file called "invoice.xps", an XML Paper Specification (XPS) file. XPS was supposed to be Microsoft's answer to PDF, and Windows has a built in XPS viewer.

Email_sample_xps
Figure 6: Email sample almost same as Figure 1 but with "invoice.xps" attachment and different email signatory

 

The attachment "invoice.xps" has FixedPage.NavigateUri property. When this is clicked, it will redirect the user to hxxp://rainbowrealty[.]com/ads/herewego.html.

Xps
Figure 7: The attachment "invoice.xps"

 

Xps_seg
Figure 8: "invoice.xps" has FixedPage.NavigateUri property


Unfortunately, this URL is no longer accessible as of this writing. It could have led to the same Ransomware or other malware. What it does show is the same actors using a variety of file formats and tricks.


An email with attachment secured with a password may give some an impression of security. But, as illustrated, it pays to be cautious. The bad guys like using passwords too, mainly to try and evade gateway inspection of the attachment.

IOC:

invoice.doc (38536 bytes)

SHA1: 6A012260238CA51FDDDAB12A5FF6FD2E1957D061

azo.exe (393216 bytes)

SHA1: 3900E2E51E8A84A730491771EE05C17EC4596962

hrms.exe (393216 bytes)

SHA1: 9DB4EAC9CBF17ACC0233F4D5808DB8F45EAF7B30

Invoice.xps (442266 bytes)

SHA1: ec688a10355c52f24f3331b4e6cbbbc23a2f4efc

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