From the National Cyber Awareness System: Major Online Ad Fraud Operation

https://www.us-cert.gov/ncas/alerts/TA18-331A

Overview

This joint Technical Alert (TA) is the result of analytic efforts between the Department of Homeland Security (DHS) and the Federal Bureau of Investigation (FBI). DHS and FBI are releasing this TA to provide information about a major online ad fraud operation—referred to by the U.S. Government as "3ve"—involving the control of over 1.7 million unique Internet Protocol (IP) addresses globally, when sampled over a 10-day window.

Online advertisers desire premium websites on which to publish their ads and large numbers of visitors to view those ads. 3ve created fake versions of both (websites and visitors), and funneled the advertising revenue to cyber criminals. 3ve obtained control over 1.7 million unique IPs by leveraging victim computers infected with Boaxxe/Miuref and Kovter malware, as well as Border Gateway Patrol-hijacked IP addresses.

Malware

Boaxxe malware is spread through email attachments and drive-by downloads. The ad fraud scheme that utilizes the Boaxxe botnet is primarily located in a data center. Hundreds of machines in this data center are browsing to counterfeit websites. When these counterfeit webpages are loaded into a browser, requests are made for ads to be placed on these pages. The machines in the data center use the Boaxxe botnet as a proxy to make requests for these ads. A command and control (C2) server sends instructions to the infected botnet computers to make the ad requests in an effort to hide their true data center IPs.

Kovter malware is also spread through email attachments and drive-by downloads. The ad fraud scheme that utilizes the Kovter botnet runs a hidden Chromium Embedded Framework (CEF) browser on the infected machine that the user cannot see. A C2 server tells the infected machine to visit counterfeit websites. When the counterfeit webpage is loaded in the hidden browser, requests are made for ads to be placed on these counterfeit pages. The infected machine receives the ads and loads them into the hidden browser.

Solution

DHS and FBI advise users to take the following actions to remediate malware infections associated with Boaxxe/Miuref or Kovter:

• Use and maintain antivirus software. Antivirus software recognizes and protects your computer against most known viruses. Security companies are continuously updating their software to counter these advanced threats. Therefore, it is important to keep your antivirus software up-to-date. If you suspect you may be a victim of malware, update your antivirus software definitions and run a full-system scan. (See Understanding Anti-Virus Software for more information.)
• Avoid clicking links in email. Attackers have become very skilled at making phishing emails look legitimate. Users should ensure the link is legitimate by typing the link into a new browser. (See Avoiding Social Engineering and Phishing Attacks.)
• Change your passwords. Your original passwords may have been compromised during the infection, so you should change them. (See Choosing and Protecting Passwords.)
• Keep your operating system and application software up-to-date. Install software patches so that attackers cannot take advantage of known problems or vulnerabilities. You should enable automatic updates of the operating system if this option is available. (See Understanding Patches and Software Updates for more information.)
• Use anti-malware tools. Using a legitimate program that identifies and removes malware can help eliminate an infection. Users can consider employing a remediation tool. A non-exhaustive list of examples is provided below. The U.S. Government does not endorse or support any particular product or vendor.