It looks like a fake jailbreak tool for iOS 4.x has been circulating recently, which claims to be using the SHAtter exploit.

Please do NOT download it as it is a trojan that steals passwords from computers.

SHAtter was a new exploit discovered by pod2g of the Chronic Dev Team, which allows the use of unsigned code execution that could jailbreak iDevices for life.

Ars Technica who were alerted about the fake jailbreaking tool by security researcher Costin Raiu at Kapersey Labs report:

A purported tool using the exploit, greenpois0n, has been circulating recently, but security researcher Costin Raiu at Kapersey Labs says that all such tools are in fact trojans designed to trick users into giving up passwords. 

Please note that the only tool available to jailbreak iOS 4.1 is Redsn0w that was released by the iPhone Dev team for iPhone 3G and iPod Touch 2G users. There is no tool available currently to jailbreak iPhone 4 or iPhone 3GS on iOS 4.1.

Chronic Dev Team had recently provided a progress update to tell us that they are still working on the tool and will let us know when it will be released.

It's important to note here that the trusted sources of such jailbreaking and unlocking tools are the iPhone Dev team and Chronic Dev Team who offer them for free, so please avoid downloading software from unknown sources.

We hope none of you have been tricked into downloading the fake tool. Please be very careful.