Interview With an Adware Author

rye writes in to recommend a Sherri Davidoff interview with Matt Knox, a talented Ruby instructor and coder, who talks about his early days designing and writing adware for Direct Revenue. (Direct Revenue was sued by Eliot Spitzer in 2006 for surreptitiously installing adware on millions of computers.) "So we've progressed now from having just a Registry key entry, to having an executable, to having a randomly-named executable, to having an executable which is shuffled around a little bit on each machine, to one that's encrypted — really more just obfuscated — to an executable that doesn't even run as an executable. It runs merely as a series of threads. ... There was one further step that we were going to take but didn't end up doing, and that is we were going to get rid of threads entirely, and just use interrupt handlers. It turns out that in Windows, you can get access to the interrupt handler pretty easily. ... It amounted to a distributed code war on a 4-10 million-node network."

Comments

Not a complete jerk

[steveha]

I'm seeing comments and tags using words like "scumbag". Well, I actually RTFA, and this guy doesn't seem to be a complete jerk.

According to him, the adware he wrote did not crack into your system using exploits, and when you ran the uninstaller it would go away and never come back. Also, according to him, it didn't scan for really personal information like credit card numbers.

I'm not about to start a fan club for him, but I don't hate him either.

I was interested in the technical stuff. His software would find other adware on a system and kick the other adware off; it was also designed to be very difficult for other adware to kick off.

The best single exchange in the interview:

S: In your professional opinion, how can people avoid adware?

M: Um, run UNIX.

steveha

Why Windows Registry is a bad idea

[whoever57]

From the interview:

We did create unwritable registry keys and file names, by exploiting an "impedance mismatch" between the Win32 API and the NT API. Windows, ever since XP, is fundamentally built on top of the NT kernel. NT is fundamentally a Unicode system, so all the strings internally are 16-bit counter Unicode. The Win32 API is fundamentally Ascii. There are strings that you can express in 16-bit counted Unicode that you can't express in ASCII. Most notably, you can have things with a Null in the middle of it.

That meant that we could, for instance, write a Registry key that had a Null in the middle of it. Since the user interface is based on the Win32 API, people would be able to see the key, but they wouldn't be able to interact with it because when they asked for the key by name, they would be asking for the Null-terminated one. Because of that, we were able to make registry keys that were invisible or immutable to anyone using the Win32 API. Interestingly enough, this was not only all civilians and pretty much all of our competitors, but even most of the antivirus people.