Challenges
RCE Challenge – nine
by sharpe on Dec.20, 2009, under Challenges, Reverse Code Engineering
My last reverseme was too easy due to the nature of the code de-obfuscation key length and usage. This time I have made some minor changes to precisely this portion of the code. Furthermore, I have added some anti-debugging stuff that I observed in a piece of malware. I hope you enjoy.
Here is a screen dump of this reverseme:
It can be downloaded here: nine (79).
RCE Challenge – eight
by sharpe on Jun.04, 2009, under Challenges, Reverse Code Engineering
Based on all the comments I have received on the previous two unlockmes (six and seven), I have created a new and improved version, which I will hope will offer more of a challenge than its predecessors. If you manage to find a valid Unlock Code, type it in and press the Unlock Code button. If it is correct, you should be able to find the hidden secret.
Here is a screen dump of this unlockme challenge:
It can be downloaded here: eight (38).
RCE Challenge – seven
by sharpe on Jun.03, 2009, under Challenges, Reverse Code Engineering
Here is my latest crackme, which is no longer a keygenme. I decided to drop that functionality as I feel that finding a valid Unlock Code for the code obfuscation is the only real challenge. If you manage to find a valid Unlock Code, type it in and press the Unlock Code button. If it is correct, things should go well when you press the Check button.
Here is a screen dump of this unlockme challenge:
It can be downloaded here: seven (38).
RCE Challenge – six
by sharpe on May.25, 2009, under Challenges, Reverse Code Engineering
All sorts of stuff is obfuscated here, including the serial-generation code as well as other “code” that may be of interest. I won’t say much more. After the unlock code has been found, type it in and it will de-obfuscate the serial generation code as with the two other challenges. If you enter an invalid code, the crackme will crash, as the de-obfuscation routine will contain garbage instruction sequences. After this bit has been complete it should be straight forward.
Here is a screen dump of this keygenme:
It can be downloaded here: six (35).
RCE Challenge – Five
by sharpe on May.18, 2009, under Challenges, Reverse Code Engineering
The serial-generation code in this crackme is obfuscated, there are no signatures this time and the entire serial generation code has been re-written. After the unlock code has been found, type it in and it will de-obfuscate the serial generation code. If you enter an invalid code, the crackme will die (depending on your luck of course), as the de-obfuscation routine may very well result in invalid instruction sequences. After this bit has been defeated, it should be straight forward.
Here is a screen dump of this keygenme:
It can be downloaded here: five (37).
RCE Challenge – Four
by sharpe on May.18, 2009, under Challenges, Reverse Code Engineering
I chose to obfuscate most of the code in this crackme besides the unlock functionality. The serial generation code is the same as in my last crackme (#3) so there will be opcode signatures that will enable you to brute out the code encryption key. If you haven’t completed my last crackme, you should still be able to find valid code signatures in the code. After the Unlock Code has been found, type it in and it will decrypt the serial generation code. Then it should be straight forward.
I figured that a good way to protect serial generation code was to obfuscate it; the code will not execute unless a valid unlock code is entered. Well the that’s the plan at least.
Here is a screen dump of this keygenme:
It can be downloaded here: four (40).
