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Title:

Password Cracking

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Password Cracking COEN 252 Computer Forensics Social Engineering Perps trick Law enforcement, private investigators can ask. Look for clues: Passwords frequently use ... – PowerPoint PPT presentation

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Title: Password Cracking


1
Password Cracking
  • COEN 252
  • Computer Forensics

2
Social Engineering
  • Perps trick
  • Law enforcement, private investigators can ask.
  • Look for clues
  • Passwords frequently use SSN, names of boyfriend,
    girlfriend, dog, sled,

3
(No Transcript)
4
Dictionary Attacks
  • Passwords need to be memorizable.
  • Most Passwords based on actual words.
  • Dictionary attacks uses a dictionary
  • Try all words in dictionary.
  • Try all words in dictionary with slight changes.
  • Typically very fast.

5
Brute Force
  • Just try out all combinations.
  • 2568 possibilities for a UNIX password.
  • But only if all letters are equally likely.
  • Not feasible on a single machine.
  • But possibly in a P2P system.
  • Using Seti_at_home technology.

6
Keystroke logging / sniffing
  • Surveillance of suspect can yield passwords.
  • Keystroke loggers can be set up to automatically
    reveal typed in passwords.
  • Same for network sniffers.

7
Default Passwords
  • Many applications come with a default password.
  • VMS used to have a default super-user password.
  • Often, the default password is the same as the
    default user name.
  • In principle, the sys-ad changes the default
    password.
  • Recently, applications are no longer shipped with
    default passwords.

8
Bios Password
  • Stored in CMOS
  • Remove power from CMOS and CMOS is reset.
  • Looses valuable forensic data such as the system
    clock.
  • Some BIOS can be programmatically cleaned.
  • Looses valuable forensic data such as the system
    clock.

9
Windows 9x
  • Windows 9x stores the login password
  • in .pwl file
  • in the c\windows directory
  • in encrypted form.
  • Obtain the password from the file.
  • Use an offline password cracker that attacks the
    weak encryption.

10
Windows 9x
  • Windows screen saver password is stored in
    user.dat file in c\windows.
  • Password is in simple ASCII encryption.
  • The screen saver password is very often the
    system password.

11
Windows NT and upUnix
  • Only hash of password is stored.
  • Computationally impossible to calculate password
    from the hash.
  • Can use the hash for a dictionary or brute force
    attack.

12
Various Applications
  • Some applications store the password in clear
    text in a hidden location.
  • Registry in Windows.
  • Some file attached to the application.
  • Or using easily breakable encryption of password
    in known place.

13
Multiple Passwords
  • Since few users can remember many passwords, any
    password for a given application might also
    unlock other passwords.
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