Rootkit.com Password Analysis

rootkit.com succumbed to a social engineering attack and more than 42000 of its user's passwords were made available on internet in clear (here). John the Ripper was used to recover the passwords. Out of curiosity, I analyzed certain aspects of passwords. The results of that analysis are shared below:

Password Lengths: The shortest password in the list was 1 character long and longest was 20 characters in length. A whopping 38.74% passwords were 6 characters in length. Here is the distribution of password lengths:

Length	Occurences	Percentage
1	16	0.04%
2	20	0.05%
3	270	0.64%
4	1444	3.41%
5	2646	6.24%
6	16424	38.76%
7	8258	19.49%
8	9786	23.09%
9	2029	4.79%
10	971	2.29%
11	250	0.59%
12	157	0.37%
13	62	0.15%
14	23	0.05%
15	8	0.02%
16	3	0.01%
17	1	0.00%
18	0	0.00%
19	2	0.00%
20	4	0.01%

Password Entropy:
Entropy of various cracked passwords was calculated using Eric Monti's rbkb's entropy function that performs chi-square calculation. Clearly, higher the entropy, lesser chances that your password will be guessed or cracked. Having said that, how easy is to remember and key in the passwords that are extremely random and are more than 16 characters in length?

Entropy	Count
0 to <1	1620
1 to <2	7388
2 to <3	32071
3 to <4	1292
4 to <5	3
5 to <6	0
6 to <7	0

Cracked Passwords with Highest Entropy: 
Certain cracked passwords had entropy in excess of 4 bits. Table below lists down the cracked passwords with highest entropy. A good dictionary allowed JTR to crack most of the passwords.

#	Entropy	Password
1	4.321928095	q1w2e3r4t5y6u7i8o9p0
2	4.321928095	1234567890qwertyuiop
3	4.321928095	1q2w3e4r5t6y7u8i9o0p
4	4	1234qwerasdfzxcv
5	3.807354922	abcdefg1234567
6	3.700439718	qwertyuiop123
7	3.700439718	superman12345
8	3.700439718	1qazxcvbnm,./
9	3.664497779	kingoftheworld
10	3.664497779	qwertyuiop[]\\
11	3.584962501	!@#$%^&*()_+
12	3.584962501	fucktheworld
13	3.584962501	1q2w3e!Q@W#E
14	3.584962501	qazxswedcvfr
15	3.584962501	123qweasdzxc
16	3.584962501	1qazxsw23edc
17	3.584962501	q1w2e3r4t5y6
18	3.584962501	asdfghjkl;\'
19	3.584962501	qwerty123456
20	3.584962501	4rfv5tgb6yhn
21	3.584962501	qwe123rty456
22	3.584962501	1qaz2wsx3edc
23	3.584962501	1a2b3c4d5e6f
24	3.584962501	123456qwerty
25	3.584962501	1q2w3e4r5t6y

Password Distribution:
Finally, I looked at password distribution. An overwhelming 51% of cracked passwords were only in lowercase, this was followed by only numeric passwords close to 24%. Passwords using uppercase alphabets along with numerics were least favorite.

Password Type	Percentage Share
Only Lowercase	51.81
Lowercase AND Numerals	23.92
Only Numeric	19.9
Alphabets (Uppercase AND Lowercase)	1.32
Alphanumeric	1.25
Passwords With Special Characters	1.11
Only Uppercase	0.45
Uppercase AND Numerals	0.24