Malvertising

When websites or web publishers unknowingly incorporate corrupted or malicious advertisements into their page, computers can become infected pre-click and post-click. It is a misconception that infection only happens when visitors begin clicking on a malvertisement. "Examples of pre-click malware include being embedded in main scripts of the page or drive-by-downloads. Malware can also auto-run, as in the case of auto redirects, where the user is automatically taken to a different site (without user interaction, such as clicking on them), which could be malicious. Malware can also be found in the delivery of an ad – where a clean ad that has no malware pre- or post-click (in its build and design) can still be infected whilst being called.[8] Malicious code can hide undetected and the user has no idea what's coming their way. A post-click malvertisement example: "the user clicks on the ad to visit the advertised site, and instead is directly infected or redirected to a malicious site. These sites trick users into copying viruses or spyware usually disguised as Flash files, which are very popular on the web."[9] Redirection is often built into online advertising, and this spread of malware is often successful because users expect a redirection to happen when clicking on an advertisement. A redirection that is taking place only needs to be co-opted in order to infect a user's computer.[1]

Malvertising affects every part of the digital advertising chain differently. From platforms to publishers, and all the way down to the end-user who may have been the victim of a malvertising attack, everyone is affected.[10] Malvertising often involves the exploitation of trustworthy companies. Those attempting to spread malware place "clean" advertisements on trustworthy sites first in order to gain a good reputation, then they later "insert a virus or spyware in the code behind the ad, and after a mass virus infection is produced, they remove the virus", thus infecting all visitors of the site during that time period. The identities of those responsible are often hard to trace, making it hard to prevent the attacks or stop them altogether, because the "ad network infrastructure is very complex with many linked connections between ads and click-through destinations."[9]

Some malvertisements can infect a vulnerable computer even if the user never clicks on the (normal-appearing) advertisement.[11]

2007/2008: The first recorded sighting of malvertising was in late 2007 to early 2008. This threat was based on a vulnerability in Adobe Flash (something that has continued into the late 2010s[12]) and affected a number of platforms including MySpace, Excite and Rhapsody.

2009: The online edition of The New York Times Magazine was found to be serving up an ad that was part of a larger click fraud scam that created a botnet network of malware-infected computers, nicknamed the Bahama botnet, that then went on to be used to carry out click fraud on pay per click ads all over the web. The banner feed of The New York Times was hacked for the weekend of September 11 to 14, causing some readers to see advertisements telling them their systems were infected and trying to trick them into installing rogue security software on their computers. According to spokeswoman Diane McNulty, "the culprit approached the newspaper as a national advertiser and had provided apparently legitimate ads for a week", and the ads were switched to the virus alert malvertisement afterwards. The New York Times then suspended third-party advertisements to address the problem, and even posted advice for readers regarding this issue on its technology blog.[13]

2010: Malvertising takes off. Marketing analysts ClickZ[14] noted that the Online Trust Alliance (OTA) identified billions of display ads, across 3500 sites carrying malware. In the same year the Online Trust Alliance[15] formed a cross industry Anti-Malvertising Task Force.

2011: Spotify had a malvertising attack which used the Blackhole exploit kit – this was one of the first instances of a drive-by download, where a user does not even have to click on an ad to become infected with malware. According to Blue Coat Systems 2012 Web Security Report,[16] 2011 saw an increase of 240% in malvertising based malicious sites.

2012: Symantec includes malvertising as a section in their Internet Security Threat Report 2013[17] which looked back at the landscape in 2012. Symantec used scanning software across a series of websites and detected that half of them were infected with malvertising. In 2012, the Los Angeles Times was hit by a massive malvertising attack which used the Blackhole exploit kit to infect users. It was seen as part of a general campaign of malvertising to hit large news portals – this strategy carried on into subsequent years with attacks on huffingtonpost.com and The New York Times.

2013: A major malvertising campaign was waged against Yahoo.com, one of the largest ad platforms with monthly visits of 6.9 billion. The malware exploit was based on the commonly used web attack, Cross-site scripting (XSS), number three in the top ten web attacks types identified by the Open Web Application Security Project[18] (OWASP). The attack infected users' machines with the ransomware Cryptowall, a type of malware that extorts money from users by encrypting their data and placing a ransom of up to $1000 in bitcoins, to be paid in 7 days, to decrypt the data.

2014: In 2014 there were major malvertising campaigns on the DoubleClick and Zedo ad networks. Various news portals, including The Times of Israel and the Hindustan Times, were affected. As in previous attacks the cybercrime involved Cryptowall as the malware infection. This spate of malvertising was believed to have brought over $1 million of ransom money in by infecting over 600,000 computers.[19]

2015: McAfee's Threat Report for February 2015 said that malvertising was growing quickly on mobile platforms.[20] In 2015 there were malvertising campaigns on eBay, Answers.com, talktalk.co.uk, and wowhead.com, among others. The campaigns involved breaches of ad networks, including DoubleClick and engage:BDR. There was also a report of possibly the first "political malvertising" campaign by pro-Russian activists, which was based on a botnet, which then forced users machines to visit bogus sites that generated ad revenue for the activists. The users also ended up at several pro-Russian propaganda videos.

Several popular websites and news sources have been victims to malvertising and have had malicious advertisements placed on their webpages or widgets unknowingly, including Horoscope.com, The New York Times,[21] the London Stock Exchange, Spotify, and The Onion.[6]

By visiting websites that are affected by malvertising, users are at risk of infection. There are many different methods used for injecting malicious advertisements or programs into webpages:

• Pop-up ads for deceptive downloads, such as fake anti-virus programs that install malicious software on the computer[2]
• In-text or in-content advertising
• Drive-by downloads[2]
• Web widgets in which redirection can be co-opted into redirecting to a malicious site[3]
• Hidden iframes that spread malware into websites[3]
• Content delivery networks exploited to share malware[3]
• Malicious banners on websites[3]
• Third-party advertisements on webpages[22]
• Third-party applications, such as forums, help desks, and customer relationship management and content management systems[22]

• Social engineering (security)
• Tech support scam

• What You Need To Know About Malvertising