Yahoo! PH Purple Hunt 2.0 Ad Compromised !
The Hacker News

Earlier the other day, I was browsing through the Yahoo! PH site and the Yahoo! Purple Hunt 2.0 ad caught my attention.

Curious as I am, I clicked on the ad and surprisingly my browser downloaded a suspicious file named

Apparently this ad redirected me to a randomly generated URL similar to the following which, unfortunately, led to the malicious download:


Below is a screenshot of the file download dialog box:
The Hacker News

The downloaded file is detected by Trend Micro as TSPY_PIRMINAY.A. Let's see how the download took place.

Firstly, the download only happens once per browser, which means that the malvertisement may have used an IP and user agent filtering of some sort to prevent multiple downloads which would make it suspicious to the end user.

To be able to replicate the malware download from the compromised ad, we used a browser extension which spoofs browser user agents, instead of installing different browsers.
The Hacker News

It appears that the advertisement is first redirected to the malware download before it finally brings the browser to the real advertisement page. The redirection follows this format for the download link:

https://{varying string}{random number}.{varying domain}/se/{constant string or guid}/

We'd like to thank the guys over at Yahoo! Ad Security Ops for acting swiftly on our initial report, taking down the malvertisement so it could no longer harm unsuspecting users.


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