New Four Step Attack Installs a Keylogger

We have talked about new Office document exploits that don’t require macros to run.  Here is a new one with more twists and turns than a mountain road.  Trustwave has reported instances of a new attack that starts as a spam or phishing email with a Word document (.DOCX) attachment.  Open the Word document and it will call out for another document download, this one in Rich Text Format (RTF) that takes advantage of known vulnerability CVE-2017-11882.  This document downloads an HTML document (HTA), that spawns Powershell with a Visual Basic script (VBS), which finally downloads a keylogger in PHP.  If all this has your head spinning, it is having a similar effect on the anti-malware software we rely on to protect us from these sorts of attacks.  Here’s the path again in a simple flowchart.

EML >> DOCX >> RTF >> HTA >> PS >> VBS >> PHP

Typical email subject lines include:

  • TNT STATEMENT OF ACCOUNT – {random numbers}……………
  • Request for Quotation (RFQ) – <{random numbers}>
  • Telex Transfer Notification
  • SWIFT COPY FOR BALANCE PAYMENT

I removed a bit of malware from a client system recently, and it had spawned a browser page that looked a lot like and Adobe Flash Player update.  See the following image.  Notice the attempted download of the HTA file, and the obviously wrong web address in the browser address bar.

You will need to be on the lookout for pages like this one.  Running the HTA file would have installed the keylogger.  A keylogger is a malware program that captures your keystrokes as you type, and is used for collecting user names, passwords, credit card number, social security numbers, and other personal information.

I encourage you to check out the Trustwave article for more examples and images.

More information:

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About the Author:

Cybersecurity analyst, pen-tester, trainer, and speaker. Owner of the WyzCo Group Inc. In addition to consulting on security products and services, Bob also conducts security audits, compliance audits, vulnerability assessments and penetration tests. Bob also teaches Cybersecurity Awareness Training classes. Bob works as an instruction for CompTIA’s non-profit IT-Ready Program in the Twin Cities. IT-Ready is a tuition free 8-week program designed to teach students of all ages the fundamentals of IT support to prepare them for an entry level position in Information Technology Support. Graduates of the classes take the exams to become CompTIA A+ certified. Bob is a frequent speaker at conferences such as the Minnesota Bloggers Conference, Secure360 Security Conference2016, 2017, 2018, 2019, the (ISC)2 World Congress 2016, and the ISSA International Conference 2017, and many local community organizations, including Chambers of Commerce, SCORE, and several school districts. Bob has been blogging on cybersecurity since 2006 at http://wyzguyscybersecurity.com

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