Hundreds of thousands of hashed corporate passwords have been cracked within minutes by penetration testers using graphics processing units.
The 626,718 passwords were harvested during penetration tests over the last two years conducted across corporate America by Trustwave infosec geeks.
The firm's threat intelligence manager Karl Sigler said in a post that half of the plundered passwords were cracked within "the first few minutes".
"We eventually cracked 576,533 or almost 92 percent of the sample within a period of 31 days," Sigler said.
"Such a short cracking time using a word list from last year’s [common passwords] study shows that passwords were as predictable as ever.
"'Password1' was the password we came across most often in this year’s analysis."
Lazy passwords allowed Trustwave hackers into every third corporate environment tested.
Passwords peaked at eight characters in keeping with business policies. The most common were Password1 with 2984 results, Hello123 with 2587, password with 2458 and welcome1 with 1697, the study found.
"Despite the best efforts of IT administrators, users find methods to meet complexity requirements while still creating weak passwords," Sigler said, noting that Active Directory's password requirements permitted 'Password1'.
Sigler reiterated warnings that mixed non-phonetic passwords riddled with special characters and numbers were no more secure than memorable phrases of the same length, provided those passwords were not common, cliche or easy to guess.
Moreover because users were more inclined to select short lengths when using non-phonetic passwords, it was easier to crack with automated tools than long phrases.
"[If] we assume the attacker knows the length of the passwords and the types of characters used, 'N^a&$1nG' could be cracked in approximately 3.75 days using one AMD R290X GPU. In contrast, an attacker would need 17.74 years to crack 'GoodLuckGuessingThisPassword' using the same GPU," the hacker wrote.
The passwords were cracked using two machines costing US$1800 and US$2700 respectively. The first ran an Intel Core i7 processor, 16Gbs of RAM and two AMD Radeon 7970 graphics cards while the second sported an AMD FX-8320 8 core processor, the same RAM and four AMD Radeon 7970 graphics cards.
The graphics card could crunch billions more calculations per second than a central processing unit for the same money. The Radeon 7970 could for US$350 run 17.3 billion NTLM hash calculations per second while a US$320 over clocked Core i7-3770K USD could only crunch 246 million calculations per second. ®
Bootnote This Reg hack recommends users select unique memorable or funny phrases for all of their important passwords, or opt for a password manager, and urges IT admins to stop forcing regular password resets since studies show this pushes users to select increasingly weaker codes. ®