2016-04-15: Sources of ReRe, a Python RE500 challenge

ReRe
The CONFidence Teaser CTF 2016 by Dragon Sector is now over and the results are in (congratz 9447!). Therefore I decided to share the sources of my task called ReRe, which was a Python rainbow-heavy obfuscation-heavy bytecode-all-around challenge. I won't spoil too much in case you would like to try to solve it (crackme/rere.py in the archive), but if you would like to read more on it, just see the SOLUTION.md file in the zip file. I'll add, that the obfuscation used self-modifying bytecode, some bytecode-level obfuscation and minor string obfuscation as well, so if you would like to learn more about Python 2.7 internal code representation, try your luck with ReRe :) It was solved 5 times btw.

Download: confidence-teaser-2016-ds-gynvael-rere.zip
"Video": rere_anim.gif (a 3 MB gif, you have been warned)

Read more... [ 6 comments ]

2016-05-30: OSDev #3 aftermath #1 - post gościnny

(Post gościnny by reenz0h)
Na ostatnim streamie OSDev#3 Gynvael kontynuował rozwijanie bootloader'a, aby ostatecznie wejść w tryb long mode. Ustawił odpowiednie parametry procesora (GDT, PAE, EFER MSR, etc.), ale próba wejścia w stronicowanie przy użyciu 1GB stron nie powiodła się. Emulator Bochs przerywał działanie z błędem "physical address not available":

<bochs:1> c
(0).[166562263] ??? (physical address not available)
Next at t=166562264
(0) [0x00000000fffffff0] f000:fff0 (unk. ctxt): jmp far f000:e05b ; ea5be000f0

Postanowiłem znaleźć trochę wolnego czasu i spróbować uruchomić ten kod u siebie.

Czytaj dalej... [ 4 komentarze ]

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