Defusing a binary bomb with gdb – Part 1(blog.carlosgaldino.com) |
Defusing a binary bomb with gdb – Part 1(blog.carlosgaldino.com) |
Not setting off the bomb is pretty easy as long as you remember to set a break point right before the "explode" function before every gdb run. Super satisfying when you get through all six stages. (there's also a secret bonus stage)
The book/course is the best designed one I've ever seen for the subject matter. Highly recommend it for anyone interested in taking it on, and on taking any course that is based on it.
Didn't see it mentioned, but the really cool thing is that the bomb required internet access and would phone home to a server to dock points if you let it go off. As you said, all it required was that one breakpoint, but it still made everything feel more critical.
Even though it is "easy" to avoid it, there were still a bunch of people who accidentally triggered it every semester.
Haven't seen the Coursera course, but it'd be really hard to make a bad course based on this book. It's both creative enough to keep attention, and doesn't skip anything.
allow me to brag a bit: I was the only one in my class to not set off the bomb!
$ objdump -s --start-address 0x402400 bomb|head
bomb: file format elf64-x86-64
Contents of section .rodata:
402400 426f7264 65722072 656c6174 696f6e73 Border relations
402410 20776974 68204361 6e616461 20686176 with Canada hav
402420 65206e65 76657220 6265656e 20626574 e never been bet
402430 7465722e 00000000 576f7721 20596f75 ter.....Wow! You
402440 27766520 64656675 73656420 74686520 've defused the
402450 73656372 65742073 74616765 2100666c secret stage!.flStudents who are really comfortable with ASM will get through it fast by reading it, and those who are less so will GDB their way to the right answer. Which is exactly how a good CS assignment should work, where it scales for each skill level very well. Hence one of the reasons this book is great!