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Tuesday, July 22, 2014

 
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One Step Ahead: Almanac Security Tips - 2014

In each issue, Penn's Journal of Record, The Almanac publishes helpful tips and hints for dealing with information security and privacy matters. This page is a collection of all those published thus far.
New! You can now receive new One-Step-Ahead Security and Privacy Tips automatically!
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Table of Contents (view all)

Heartbleed OpenSSL Vulnerability
Security and Privacy Tips for World Travelers
Filing Taxes Online This Year? Take Steps to Protect Your Information!
If your computer runs Windows XP, you must update it now!
Why Should You Report Security Incidents? And How Do You Report One?
Photo and Video Privacy Issues
The Password is Dead, Long Live the Password!
Data Privacy Month: NSA Surveillance Panel at the National Constitution Center
Protecting Your Finances During This Year’s Holiday Shopping Season
Beware of Phishing E-mails in the Wake of Typhoon Haiyan
No E-mail from Penn Will Ask For Your Username/Password or SSN
The Children's Online Privacy Protection Act: Does It Apply to Your Website?
October: National Cyber Security Awareness Month; Free Secure Disposal of Paper and Electronics
What Basic Rules Protect Student Information at Penn? (September 2013)
Protecting Privacy and Security on Penn + Box


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Tagged with security , passwords

Tuesday, October 20, 2009 - Almanac Vol. 56, No. 8

Password Cracking: The Pot of Gold at the End of the Rainbow

One of the "holy grails" coveted by hackers when they compromise a system is the file which contains the passwords for all the users on that system. The passwords are stored in encrypted form, of course, but if a hacker can decode or "crack" the encryption the reward is a valuable set of user credentials, especially if the system in question is a large, heavily used server. "Cracker’s Dictionaries" have been used for this purpose for several years, and these typically are pre-compiled lists of more than one million potential passwords comprising not only all known English words (including proper nouns), but also variations used on them, e.g. "crooked" and "cr00k3d".

In recent years, however, hackers have also made extensive use of "rainbow tables," a sort of "reverse dictionary" which contains the encrypted values for all possible passwords of a given length, indexed to their associated passwords. It sounds unbeatable, but there *are* limitations. Rather than mere hundreds of thousands of entries, "rainbow tables" will sometimes contain entries numbering into 25 digits or more (septillions), and this requires enormous amounts of memory and disk space to make use of. Also, many computer systems "salt" their password files with special added data that diminish the effectiveness of these attacks, though some systems (especially older Windows systems) have been shown to be vulnerable. One researcher, using a widely available "rainbow" tool, reported cracking a Windows password "Fgpyyih804423" in less than three minutes!

Most cracking dictionaries and rainbow tables tend to discount or overlook the use of "special characters" in passwords (those produced using the 'Shift' key and the top row of the keyboard - !, @, #, $, etc.), so using one or more of these when selecting a password is good protection against its being "cracked."

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