Beside a hard drive failure or discovering a scratch on a backup DVD, one of most frustrating user-induced experiences is forgetting a password for that all-important spreadsheet or a word document containing masters’ thesis or something similar.

Russian cryptologists from ElcomSoft think that they have just the right "silver bullet" for Excel and Word documents. Following the footsteps of their Thunder Tables for Microsoft Word, this security giant released Rainbow Tables for Microsoft Excel. According to the company, Thunder Tables comes with a 100% guarantee that it will recover a password from a word document containing Microsoft-standard 40-bit encryption. In case of Rainbow Tables, the company guarantees near-instant recovery of 97% spreadsheets saved using Excel 97-2000 file. According to statements given by ElcomSoft’s CEO, Mr. Vladimir Katalov, Rainbow Tables cannot offer 100% password rate "due to difference in file formats between Microsoft Word and Office". Still, the possibility of near-instant opening every word document out there is pretty scary, if not used for their own purposes. Given the list of ElcomSoft’s customers, we can only wonder what the company sells to international security organizations such as Interpol or three-letter agencies in the US. 

There is no "silver bullet" for password cracking, though. The company released Rainbow and Thunder Tables on a DVD containing pre-computed hash tables. The only limit to the pre-computed hash tables is the amount of available space of this Dual-Layer DVD. If the algorithm fails to find appropriate pre-computed key, it will perform a conventional brute force method, resulting in password breaking lasting for up to 48 hours using modern computers.

Both Rainbow and Thunder Tables are a part of Advanced Office Password breaker suite, but the company didn’t raise the price of the suite – it still ranges between $99 and $399.