A cracker does exist for Winrar 3.0 BUT
Winrar 3 is now using the
AES-128 Standard Encryption, so even if you did have a cracker for it and ......
"Assuming that one could build a machine that could recover a DES key in a second (i.e., try 255 keys per second), then it would take that machine approximately 149 thousand-billion (149 trillion) years to crack a 128-bit AES key."
So if a site says that they have a winrar 3 cracker, technically they may but you may want to sit down and have a coffee while your computer tries to crack the code. Most of the sites that say they have a winrar 3 crack are usually filled with malicious scripts and hacks so beware.