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.

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About the Author:

Cybersecurity guru to business owners in the St Paul, Minneapolis, and western Wisconsin area. Computer security and hacking have been a passion of mine since I entered the computer and networking business in 2000. In 2013 I completed a course of study and certification exam to become a Certified Ethical Hacker (CEH). In 2016 I was certified as a Certified Information Systems Security Professional (CISSP). As Cybersecurity Analyst at The WyzCo Group, I help our clients experience high levels of computer security, network security, and web site security. In addition to consulting on security products and services, we also conduct security audits, vulnerability assessments and full penetration tests. We also provide Cybersecurity Awareness Training for clients and their employees. We also work with companies and organizations that need to certify compliance with regulations such as PCI-DSS (credit card processing), HIPAA/HITECH (medical records), and GLBA. The views expressed on this Web site are mine alone and do not necessarily represent the views of my employer.

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