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Ask HN: What's your proudest hack?

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Re: Ask HN: What's your proudest hack?

#151

Post by conorcleary »

nemo1618 wrote: post #109

After playing a lot of Tetris Friends, I started getting deja vu. Sometimes, after starting a new game and placing maybe 10-20 pieces, I would think, "Haven't I seen this exact board before?" Eventually I tested my theory through brute force: I would start a fresh game, write down the first 10 pieces, then restart. Over and over and over, until finally, I found it -- a duplicate! Apparently, Tetris Friends only seede…

I had a similar experience about a decade ago with an online rock-paper-scissors vs. computer site. I quickly figured out the pattern and was able to win a few dozen times in a row (late night) and got bored, but it was a very intriguing exercise.

Re: Ask HN: What's your proudest hack?

#152

Post by jemfinch »

I once really enjoyed a shareware game on my MacBook pro named "Galcon". I enjoyed this game so much I was considering buying the complete version, but it was a bit pricey and I really wanted to know whether the unlocked content would be worth the $20 for an unlock key.

I realized the game was written in Python and dug into the .app directory. It was mostly binary data, but there was one python script with two lines, essentially "import game" and "game.start()". I inserted a pdb checkpoint between those two lines and started the game, dropping into a terminal with the game module loaded. I started peering around with "dir" and ended up finding the function which validated purchase keys, so I replaced it with "return true" and I was able to see the unlockable content.

Unsatisfied with just that, next I used the "dis" module to disassemble the key validation function, decompiled it by hand into python code, and inverted it to make a function which could generate arbitrary keys.

Then I revealed all this to the author and he never got back to me.

Re: Ask HN: What's your proudest hack?

#153

Post by dansult »

mprime1 wrote: post #37

Very low tech, but helps me communicate privately with friends and family over non-private channels (like email). Also use it to store critical password and keys, and have copies of my passport with me everywhere. https://github.com/mprimi/portable-secret

This is really cool. I can see this being a very useful tool, especially for helping out my folks and tech illiterate family.

Re: Ask HN: What's your proudest hack?

#154

Post by young_hopper »

tiffanyh wrote: post #83

Elementary school, Windows 3.x era. School district thought they blocked access to the built-in OS games. Nope, from any program (Wordpad, etc) you could FILE -> OPEN to find/launch/play Minesweeper. Nothing makes an 8-year-old feel more like a "hacker" than subverting school controls to play video games, while also gaining cred with your friends. The good ol' days.

Reminds me of high school. We also had locked down computers, but one day I noticed that one of the programs on the system had a directory structure of hundreds, if not thousands, of executable plugins that needed run-access for the program to execute properly.

My hypothesis was that the IT guys were lazy and just unblocked anything in that directory. Even if a networked computer didn't have this program on it, you could just recreate the directory structure and drop any portable executable there and run it. Pretty soon we were all playing brood war in every free period.

Re: Ask HN: What's your proudest hack?

#156

Post by b0afc375b5 »

alhirzel wrote: post #100
AlexSW wrote: post #89

Earlier quoted context omitted.

How did you get it out of RAM so cleanly?

It wasn't clean, I had to manually parse it out of /proc and triple check the math before committing it with fdisk.

Do you have a blog post about this with more details somewhere?

Re: Ask HN: What's your proudest hack?

#157

Post by FrostKiwi »

alhirzel wrote: post #100
AlexSW wrote: post #89

Earlier quoted context omitted.

How did you get it out of RAM so cleanly?

It wasn't clean, I had to manually parse it out of /proc and triple check the math before committing it with fdisk.

That's pretty hard core. Any resources you recommend to understand the steps involved? Maybe a write-up by yourself?

Re: Ask HN: What's your proudest hack?

#158

Post by FrostKiwi »

b0afc375b5 wrote: post #156
alhirzel wrote: post #100

Earlier quoted context omitted.

It wasn't clean, I had to manually parse it out of /proc and triple check the math before committing it with fdisk.

Do you have a blog post about this with more details somewhere?

Haha, posted the same message at the same time. Great minds think alike ;]

Re: Ask HN: What's your proudest hack?

#159

Post by conductr »

rcarr wrote: post #80
conductr wrote: post #61

Earlier quoted context omitted.

It was a lot of logistics with physical cash. But yeah I tried to run it as close to "real" as possible in case I did hit legal issues (isolating the entities, not comingling funds). Also, had to make sure for taxes that the cycled cash wasn't possibly viewed as income to either entity. There were a few optimization steps I found that helped me streamline the logistics but I still was withdrawal-ing cash from the ATM…

How did you discover these loopholes in the first place? Did you work in the finance industry or an ATM maker or something like that and just figured it out?

Can’t say I remember exactly. No particular experience other than a general knack for spotting loopholes like this.

If I remember correctly I had some vague knowledge that basically anyone can own an ATM and set the surcharge as they want. I probably looked into it as a passive income stream at some point (these things had a high growth phase some time ago). Then I think the first time I heard about ATM rebates was on an advert of some sort and the whole thing seemed obvious. So I looked into the fine print and it seemed to check out.

I don’t think this was ever a thing until online banks came around during Web 1.0 , traditional banks would charge you a fee for using out of network ATMs (which is still pretty standard), but the online banks resorted to offering surcharge rebates as a way to compete with brick and mortar banks. And also to overcome the obvious pushback of people wanting quick access to their cash. Then smaller banks started offering it as a way to compete with the national banks that have huge ATM networks.

Re: Ask HN: What's your proudest hack?

#160

Post by Tijdreiziger »

tiffanyh wrote: post #83

Elementary school, Windows 3.x era. School district thought they blocked access to the built-in OS games. Nope, from any program (Wordpad, etc) you could FILE -> OPEN to find/launch/play Minesweeper. Nothing makes an 8-year-old feel more like a "hacker" than subverting school controls to play video games, while also gaining cred with your friends. The good ol' days.

Ha, reminds me of high school. No command line access on the school PCs.

At the time, I was learning PHP, having stepped up from plain HTML/CSS. I had also discovered that I could run a web server (XAMPP).

So, one PHP script later, and sure enough… command line access through the browser!

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