![]() Here we are creating three different character sets. To do this, we will create a custom charset which makes our next portion of the command like so: -1 ?u -2 ?u?l?d -3 ?d However, in our case, we need to be more specific. We can see that the built-in charsets can be used to specify a useful range of characters. 4, -custom-charset4=CS -2 mycharset.hcchr : sets charset ?2 to chars contained in file 3, -custom-charset3=CS -custom-charset1=?dabcdef : sets charset ?1 to 0123456789abcdef 1, -custom-charset1=CS User-defined charsets This is because it’s possible to perform a traditional brute-force attack if the mask specifies every possible character to try.īelow are the mask commands from “hashcat -help” * Built-in charsets: Note that although this method isn’t regarded as a proper brute-force attack, it has replaced the brute-forcing function in hashcat. So far we are specifying our hash as MD5 (-m 0) and our attack mode as a brute-force (-a 3). a, -attack-mode=NUM Attack-mode, see references belowīased on the above the start of our command looks like the following: hashcat –m 0 –a 3 m, -hash-type=NUM Hash-type, see references below Knowing this, as already explained will reduce the number of combinations needed to try even more.įrom the output of “hashcat –help” we'll use the following information to perform our mask attack: * General: To speed up the process of the cracking, we are going to base this attack on us knowing the last three characters are numbers and the first one is also a capital letter. So now that we have the hash we want to perform our mask attack on, we will now define our mask. If that doesn’t work on your system you can run this command to store the hashed password in a file: echo -n "bde14596c16536af673ce451f25b2a94" > hash Understanding the hashcat parameters This command is explained in a previous blog post but to summarise it creates an MD5 hash of whatever text is echoed and stores it in a file called hash. On my system running Kali Linux, I can run the following command to generate a file containing the hashed word: echo -n "Mask101" | md5sum | tr -d " -" > hash A lot of home router's have default password generation algorithms and information about their keyspace can be found online. ![]() For example, a common habit is for passwords to start with a capital if at least one is required.Īnother example where masking can be applied is that if default passwords schemes use a known set of characters. Using masking you can also create masks to exploit password habits. Of course you need to make sure your information on the password is correct, otherwise your mask may not generate the password. This would drastically reduce the potential keyspace as no passwords with any letter or symbol in the last three spaces would need to be tried. Now suppose we know the last three characters are numbers. It has a length of 7 characters and for each one, it could be upper-case (26 potential characters), lower-case (26 potential characters), a symbol (33 potential characters) or a number (10 potential characters), we’d have to try a total number of 95^7 (69,833,728,698,375) combinations. This matters because the total combination of characters to exhaust with a masking attack is smaller.įor example, if we take the following password: Mask101 Using traditional brute-force attacks, you would still be forced to try characters that are not numbers. Mask attacks are more specific as the set of characters you try is reduced based on information you know.įor example, if you know the last character in a password is a number, you can configure your mask to only try numbers at the end. With brute-force attacks, all possible characters that exist are tried. Mask attacks are similar to brute-force attacks given they try all combinations from a set of characters. Some commands may differ on other systems but the process is the same. ![]() This guide is demonstrated using the Kali Linux operating system by Offensive Security. To demonstrate, we will perform a mask attack on a MD5 hash of the password “Mask101”. We will specify masks containing specific ranges using the command line and with hashcat mask files. In this tutorial we will show you how to perform a mask attack in hashcat.
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