One of the most impressive hacks I've ever read about has to be the Black Sunday kill. Since the original 2001 Slashdot article I read on this is 99.9% quote, I'm going to do the same. I can see why they quoted so extensively; it'd be difficult to improve on the unusually succinct, well written summary provided by Pat from Belch:

One of the original smart cards, entitled 'H' cards for Hughes, had design flaws which were discovered by the hacking community. These flaws enabled the extremely bright hacking community to reverse engineer their design, and to create smart card writers. The writers enabled the hackers to read and write to the smart card, and allowed them to change their subscription model to receive all the channels. Since the technology of satellite television is broadcast only, meaning you cannot send information TO the satellite, the system requires a phone line to communicate with DirecTV. The hackers could re-write their smart cards and receive all the channels, and unplug their phone lines leaving no way for DirecTV to track the abuse. DirecTV had built a mechanism into their system that allowed the updating of these smart cards through the satellite stream. Every receiver was designed to 'apply' these updates when it received them to the cards. DirecTV applied updates that looked for hacked cards, and then attempted to destroy the cards by writing updates that disabled them. The hacking community replied with yet another piece of hardware, an 'unlooper,' that repaired the damage. The hacker community then designed software that trojanized the card, and removed the capability of the receivers to update the card. DirecTV could only send updates to the cards, and then require the updates be present in order to receive video. Each month or so, DirecTV would send an update. 10 or 15 minutes later, the hacking community would update the software to work around the latest fixes. This was the status quo for almost two years. 'H' cards regularly sold on eBay for over $400.00. It was apparent that DirecTV had lost this battle, relegating DirecTV to hunting down Web sites that discussed their product and using their legal team to sue and intimidate them into submission.

Four months ago, however, DirecTV began sending several updates at a time, breaking their pattern. While the hacking community was able to bypass these batches, they did not understand the reasoning behind them. Never before had DirecTV sent 4 and 5 updates at a time, yet alone send these batches every week. Many postulated they were simply trying to annoy the community into submission. The updates contained useless pieces of computer code that were then required to be present on the card in order to receive the transmission. The hacking community accommodated this in their software, applying these updates in their hacking software. Not until the final batch of updates were sent through the stream did the hacking community understand DirecTV. Like a final piece of a puzzle allowing the entire picture, the final updates made all the useless bits of computer code join into a dynamic program, existing on the card itself. This dynamic program changed the entire way the older technology worked. In a masterful, planned, and orchestrated manner, DirecTV had updated the old and ailing technology. The hacking community responded, but cautiously, understanding that this new ability for DirecTV to apply more advanced logic in the receiver was a dangerous new weapon. It was still possible to bypass the protections and receive the programming, but DirecTV had not pulled the trigger of this new weapon.

Last Sunday night, at 8:30 pm est, DirecTV fired their new gun. One week before the Super Bowl, DirecTV launched a series of attacks against the hackers of their product. DirecTV sent programmatic code in the stream, using their new dynamic code ally, that hunted down hacked smart cards and destroyed them. The IRC DirecTV channels overflowed with thousands of people who had lost the ability to watch their stolen TV. The hacking community by and large lost not only their ability to watch TV, but the cards themselves were likely permanently destroyed. Some estimate that in one evening, 100,000 smart cards were destroyed, removing 98% of the hacking communities' ability to steal their signal. To add a little pizzazz to the operation, DirecTV personally "signed" the anti-hacker attack. The first 8 computer bytes of all hacked cards were rewritten to read "GAME OVER".

Nobody knew how the satellite companies had suddenly developed such smarts. Until now. A recent Wired article exposes Christopher Tarnovsky as the mind behind the epic Black Sunday Hack.

Among the countermeasures he says he created was one known among pirates as the "Black Sunday" kill -- an elaborate scheme that destroyed tens of thousands of pirate DirecTV cards a week before Super Bowl Sunday in 2001.

Instead of being delivered all at once like other measures, the Black Sunday attack code was sent to pirate cards in about five dozen parts over the course of two months, like a tank transported piece by piece to a battlefield to be assembled in the field. "They never expected us to do this," Tarnovsky says.

The kill didn't last long before pirates found a way to jump-start the cards. But it holds an enduring position in pirate lore; for the first time, they could see a cunning mind at work on the other side.

It's fascinating to finally hear the Black Sunday kill described so intimately from the inside. It's a gripping tale of high stakes programming, a life of electronic warfare with millions of dollars at risk on both sides. I've never been a satellite television subscriber, but apparently the war rages on even today -- at least according to the Wikipedia entry on pirate decryption.