Each word of a dictionary is appended to each word in a dictionary.

If our dictionary contains the words:

pass
12345
omg
Test

Hashcat creates the following password candidates:

passpass
pass12345
passomg
passTest
12345pass
1234512345
12345omg
12345Test
omgpass
omg12345
omgomg
omgTest
Testpass
Test12345
Testomg
TestTest

Using the Combinator Attack within hashcat (not standalone version of Combinator Attack).

The command for the Combinator Attack in hashcat is -a 1

You need to specify exactly 2 dictionaries in you command line: e.g.

./hashcat64.bin -m 0 -a 1 hash.txt dict1.txt dict2.txt

If you wish to add rules to either the left or right dictionary or both at once then you can use the -j or -k commands.

  -j,  --rule-left=RULE              Single rule applied to each word on the left dictionary

  -k,  --rule-right=RULE             Single rule applied to each word on the right dictionary

Example.

Dictionary 1

yellow
green
black
blue

Dictionary 2

car
bike

Commands

-j '$-'

-k '$!'

Note: the quotes are only there to escape the $ character, which would otherwise allow $- to be interpreted as a variable. The rules that are used here are still just $- and $!. Escaping might not work exactly the same way on each operating system and with each shell interpreter (if you are unsure about what needs to be escaped and how it should be escape, please consider looking up your OS and/or shell interpreter manual).

The output would be…

yellow-car!
green-car!
black-car!
blue-car!
yellow-bike!
green-bike!
black-bike!
blue-bike!