B FOR 204 Lecture Notes - Lecture 5: Packet Analyzer, Dictionary Attack, Intrusion Detection System
2 Jun 2018
School
Department
Course
Professor
Making Our Systems Less Vulnerable
BFOR 204
Network and System Security
Security
• Maintaining an appropriate level of computer security requires attention to
confidentiality, integrity and availability.
Intruders
• Significant issue for networked systems is hostile or unwanted access.
o Unauthorized users
• Either via network or local
• Varying levels of competence
o key goal often is to acquire passwords
Protecting systems from intruders
Password Management
• front-line defense against intruders
• users supply both:
o login – determines privileges of that user
o password – to identify them
• passwords often stored encrypted
o Unix uses multiple DES (variant with salt)
o more recent systems use hash function
Password Cracking
• Two steps
1) Obtain the hash of the password
o Hash – It is a value that is calculated by processing the text of a
password through an algorithm.
o Salt - It is random data that is used as an additional input to an
algorithm that "hashes" a password.
2) Crack the password!
o Using a cracking program.
o Can’t reverse the hash back to the password.
o But can create a password using the hash.
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