The Microsoft Publisher Documents utilized as a part of this battle was gone for infecting the victim with the, well known, Pony malware. While Pony is all around archived in specialized capacity it has not been known to utilize the .bar document organize as of not long ago.

Horse is an accreditation collecting bit of malware with other trojan abilities.

Notwithstanding accreditation gathering, it is likewise regularly conveyed as a malware loader and used to contaminate frameworks with extra malware in multi-arrange disease chains.

As researchers at Cisco Talos .,

Talos has observed a small email campaign leveraging the use of Microsoft Publisher files. These .pub files are normally used for the publishing of documents such as newsletters, allowing users to create such documents using familiar office functions such as mail merging.

Unlike other applications within the Microsoft Office suite, Microsoft Publisher does not support a ‘Protected View‘ mode. This is a read only mode which can help end users remain protected from malicious document files. Microsoft Publisher is included and installed by default in Office 365.

Horse is still utilized vigorously as the wellsprings of numerous Pony adaptations spilled in this way making it much less demanding for different noxious performing artists to actualize Pony into their disease chain.

The credential-stealing Pony malware is masquerading as Microsoft Publisher documents in an effort to infect unsuspecting users.

The Pub

This campaign was delivered using email attachments which is a very common method of infection for old and new malware. The difference here is the use of .pub files. The attached file was delivered to the end user as “” the attacker made no attempt to try to hide the file type. Frequently we see attackers hiding the true file type within a .zip compressed file. However, the ‘SKBMT’ name can be misread as part of the ‘SKMBT’ prefix used by Konica Minolta scanner (SKMBT – Scan Konica Minolta Business Technologies). The file was a seemingly legitimate Microsoft Publisher file.

The campaign begins when an attack email containing a Microsoft Publisher document saunters over to an unsuspecting user.

Those individuals behind this campaign don’t seem too worried about that. Otherwise, they would have tried to have concealed the attachment’s file type, such as by hiding it within a compressed .ZIP file. Instead they use some social engineering techniques to bait the user into clicking on the attachment. If they succeed, the user opens the document, which soon after appears to crash.


In the background, there’s a 2MB macro that’s up to no good. The file capitalizes on the user’s confusion by writing a “letten.js” file onto disk. This file comes with its own protective measures.


Talos Said, Upon completion of our analysis we identified the malware payload as Pony. Pony is not a new piece of malware and is well documented and well understood by the security community. Pony is mainly used for password stealing and credential harvesting.

The use of the .pub file as a delivery mechanism and the obfuscated Javascript was the new features within this Pony campaign. A small point of note was this campaign was relatively unsuccessful in terms of outbound connectivity. Using Cisco Umbrella we were able to identify a low number of connections to the C2 infrastructure.

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BALAJI is an Ex-Security Researcher (Threat Research Labs) at Comodo Cybersecurity. Editor-in-Chief & Co-Founder - Cyber Security News & GBHackers On Security.


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