Transcript What are Rainbow Tables?

What are Rainbow Tables?
• Passwords stored in computers are changed from
their plain text form to an encrypted value.
• These values are called hashes, and there is a unique
plain text value for every hash.
A rainbow table is a lookup table offering a timememory tradeoff used in recovering the plaintext
password from a password hash generated by a
hash function
Approach invented by Martin Hellman
What Are Rainbow Tables?
• The concept behind rainbow tables is simple
• Make one-way hash functions two way by making a list of outputs for
all possible inputs up to a character limit
• Rainbow Tables are built once, and used many times
• Fast
• Password lookups become a table search problem
• The brute force work is pre-computed
• Perfect for cracking weak hashes
• Windows LM hashes of 14 characters or less can be cracked with trivial effort
• Any non salting password hash can be cracked easily
Rainbow table Cracking
Download one of the latest version and then extract it(we use windows version)–
http://project-rainbowcrack.com
• It includes three tools:
• rtgen program to generate rainbow tables.
• rtsort program to sort rainbow tables generated by rtgen.
• rcrack program to lookup rainbow tables sorted by rtsort.
• It also has a .txt file with name "charset.txt“ and it
contains all the available set of chars used to generate
the tables.
Generate a Rainbow Table
Default Syntax of the command:
rtgen hash_algorithm charset plaintext_len_min plaintext_len_max table_index chain_len
chain_num part_index
Command:
$rtgen md5 loweralpha-numeric 1 5 0 10000 9682 0
Description: Continue those commands to generate more tables$rtgen md5 loweralpha-numeric 1 5 1 10000 9682 0
• hash_algorithm can be: LM, NTLM, MD5
$rtgen md5 loweralpha-numeric 1 5 2 10000 9682 0
• charset $rtgen
can be:
alpha-numeric,
loweralpha-numeric,
md5
loweralpha-numeric
1 5 3 10000 9682 0 etc.
$rtgen md5 loweralpha-numeric
1 5 4 10000
0 code.
• plaintext_len_min
describes the minimum
length9682
of hash
• plaintext_len_max describes the maximum length of hash code.
• table_index describes the order of the tables.
• chain_len describes the length of each "rainbow chain".
• chain_num describes the number of rainbow chains in the
rainbow table.
• part_index determines how the "start point" in each rainbow chain
is generated
Sort Rainbow Tables
• rtsort program is used to sort the "end point" of all rainbow
chains in a rainbow table to make table lookup easier.
The syntax of the command line is:
$rtsort md5_ loweralpha-numeric#1-5_0_10000x9682_0.rt
$rtsort md5_ loweralpha-numeric#1-5_1_10000x9682_0.rt
$rtsort md5_ loweralpha-numeric#1-5_2_10000x9682_0.rt
$rtsort md5_ loweralpha-numeric#1-5_3_10000x9682_0.rt
$rtsort md5_ loweralpha-numeric#1-5_4_10000x9682_0.rt
Crack Hashes
• Use rcrack tool to lookup the rainbow tables for the suitable - required Hash code.
• The default syntax of the command is:
crack /the/directory/of/*.rt -option hash_code
Here option can be:
-h: use_hash_directly_here
-f : pwdump_file
-l : hash_list_file
Command:
$rcrack *.rt -h D9DA8170E8BC9F27B2D32A6C9A6C697D
The plain text password of the given hash with reasonable time and memory will be shown
Edit Charset.txt List
• We can also change the character set from the character.txt file$set_cahr_name =[my,chars,-,symbols]
For more details:
http://www.liatsisfotis.com/2013/01/crack-hashes-using-rainbowtables.html
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LastPass
• https://www.youtube.com/watch?v=RM0fzHxMASQ
LastPass
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