Cracking the Hashes

Hack Responsibly.

Always ensure you have explicit permission to access any computer system before using any of the techniques contained in these documents. You accept full responsibility for your actions by applying any knowledge gained here.

Password Hashes

Identifying Hashes

MD5 = 32 hex characters
SHA-1 = 40 hex characters
SHA-256 = 64 hex characters
SHA-512 = 128 hex characters

Find the type of hash:

hash-identifier

Running john with no parameters will attempt to tell you the hash type:

john $hash_list

Hash Cracking

Hashcat basic syntax:

hashcat -m $hash_type -a $mode -o $out_file $hash_file $pass_list

John the Ripper basic syntax:

john --wordlist=$pass_list --format $hash_format $hash_list

Convert hashes from /etc/shadowto a crackable format (then use john to crack):

unshadow $etc_password $etc_shadow > $unshadowed_outfile

Generating wordlists

crunch

#hashcat can make a huge variety of different passwords using many 
#different mangling rules or masks

hashcat --outfile > $hash_file

Online rainbow tables:

  • https://crackstation.net/

  • http://www.cmd5.org/

  • https://hashkiller.co.uk/md5-decrypter.aspx

  • https://www.onlinehashcrack.com/

  • http://rainbowtables.it64.com/

  • http://www.md5online.org

  • https://www.cmd5.org/

  • http://hashes.org

  • https://gpuhash.me/

  • https://crack.sh/

  • https://hash.help/

  • https://passwordrecovery.io/

  • http://cracker.offensive-security.com/

  • https://md5decrypt.net/en/Sha256/

  • https://weakpass.com/wordlists

Hashcat Cheatsheet

Hashcat Cheatsheet for OSCP https://hashcat.net/wiki/doku.php?id=hashcat​

Identify Hashes

hash-identifier

Example Hashes: https://hashcat.net/wiki/doku.php?id=example_hashes​

MOAR POWAR!

I have found that I can squeeze some more power out of my hash cracking by adding these parameters:

--force -O -w 4 --opencl-device-types 1,2

These will force Hashcat to use the CUDA GPU interface which is buggy but provides more performance (–force) , will Optimize for 32 characters or less passwords (-O) and will set the workload to "Insane" (-w 4) which is supposed to make your computer effectively unusable during the cracking process. Finally "--opencl-device-types 1,2 " will force HashCat to use BOTH the GPU and the CPU to handle the cracking.

Using a dictionary

Hashcat example: cracking Linux md5crypt passwords (identified by $1$) using a wordlist:

hashcat --force -m 500 -a 0 -o $out_cracked_passes $hash_file $pass_list

Hashcat example cracking WordPress passwords using a wordlist: hashcat --force -m 400 -a 0 -o $out_cracked_passes $hash_file $pass_list

Sample Hashes http://openwall.info/wiki/john/sample-hashes​

One Rule to Rule Them All

@NotSoSecure has built a custom rule that combines many of the most popular Hashcat rules: https://www.notsosecure.com/one-rule-to-rule-them-all/

The rule can be downloaded from GitHub: https://github.com/NotSoSecure/password_cracking_rules​

Put the OneRuleToRuleThemAll.rule file into the /usr/share/hashcat/rules/ folder and run it:

hashcat -D1,2 -O --force -m300 --status -w3 -o $out_cracked_passes -r /usr/share/hashcat/rules/OneRuleToRuleThemAll.rule $hash $pass_list

Using Hashcat for brute-forcing

Predefined character sets:

?l = abcdefghijklmnopqrstuvwxyz
?u = ABCDEFGHIJKLMNOPQRSTUVWXYZ
?d = 0123456789
?s = «space»!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~
?a = ?l?u?d?s
?b = 0x00 - 0xff

?u?l?d is the same as: ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789

Brute-force all passwords of length 1-8 with these possible characters: A-Z a-z 0-9 hashcat -m 500 $hash_file -a 3 --increment -1 ?l?d?u ?1?1?1?1?1?1?1?1

Cracking Linux Hashes from /etc/shadow file

Cracking Windows Hashes

Cracking Common Application Hashes

Cracking Common File Password Protections

Cracking Commmon Database Hash Formats

Cracking NTLM hashes

After grabbing or dumping the NTDS.dit and SYSTEM registry hive or dumping LSASS memory from a Windows machine:

Using Impacket to dump the hashes:

impacket-secretsdump -system SYSTEM -ntds ntds.dit -hashes lmhash:nthash LOCAL -outputfile ntlm-extract

You can crack the NTLM hash dump usign the following hashcat syntax:

hashcat -m 1000 -a 0 -w 4 --force --opencl-device-types 1,2 -O $hash_file $pass_list -r /usr/share/hashcat/rules/OneRuleToRuleThemAll.rule

Cracking KRB5TGS Hashes - "Kerberoasting"

A service principal name (SPN) is a unique identifier of a service instance. SPNs are used by Kerberos authentication to associate a service instance with a service logon account. This allows a client application to request that the service authenticate an account even if the client does not have the account name. These SPNs cat be collected by using a username list and Impacket's example scripts. After gathering a list of valid usernames that have the property ‘Do not require Kerberos pre-authentication’ set (UF_DONT_REQUIRE_PREAUTH), you can get the SPN hash for cracking, replay, or creating of Kerberos tickets using the example below.

python GetNPUsers.py -dc-ip $DC_IP $DOMAIN/ -usersfile $users_list -format hashcat -outputfile $out_hash_list

python GetUserSPNs.py -request -dc-ip $DC_IP $DOMAIN/$valid_user

Hashcat supports multiple versions of the KRB5TGS hash which can easily be identified by the number between the dollar signs in the hash itself.

  • 13100 - Type 23 - $krb5tgs$23$

  • 19600 - Type 17 - $krb5tgs$17$

  • 19700 - Type 18 - $krb5tgs$18$

KRB5TGS Type 23 - Crackstation humans only word list with OneRuleToRuleThemAll mutations rule list.

hashcat64 -m 13100 -a 0 -w 4 --force --opencl-device-types 1,2 -O d:\krb5tgs.hash d:\WORDLISTS\realhuman_phill.txt -r OneRuleToRuleThemAll.rule

To crack Linux hashes with John you must first unshadow them

unshadow $passwd $shadow > unshadowed.txt

Crack a zip password

zip2john Zipfile.zip | cut -d ':' -f 2 > hashes.txt hashcat -a 0 -m 13600 hashes.txt /usr/share/wordlists/rockyou.txt

Hashcat appears to have issues with some zip hash formats generated from zip2john. You can fix this by editing the zip hash contents to align with the example zip hash format found on the hash cat example page: $zip2$*0*3*0*b5d2b7bf57ad5e86a55c400509c672bd*d218*0**ca3d736d03a34165cfa9*$/zip2$

John seems to accept a wider range of zip formats for cracking.

John the ripper: john --wordlist=/usr/share/wordlists/rockyou.txt <hash_file>

Jumbo John = Better than original john

Hashes.org: large database of pre-cracked hashes

Many password lists to download at skullsecurity

21.1GB wordlist of passwords! (Smaller samples available too) https://md5decrypt.net/en/Password-cracking-wordlist-download/

Hash formats list for hashcat

Brute-force crack password with known format:

hashcat -m <1600 (hashtype)> <hash.txt> --force -a 3 -1 <char_set> ?1?1?1?1?1?1?1?1 -O
[?1 = use 1 char from '1' set] 5KFB6

Create wordlist of 'words' with known character-set & length:

crunch <8 (min_length)> <8 (max_length)> <aefhrt (char_set)> > wordlist.txt

Generate password for insertion directly into /etc/passwd (assumes write privilege to that file):

openssl passwd -l [or 1?] -salt <any_salt_value> <password> 
<username>:<generated_pass>:0:0:root:/root:/bin/bash #enter into /etc/passwd like this

Custom Code Examples

Decrypt LDAP Passwords

https://dotnetfiddle.net/2RDoWz

using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;
					
public class Program
{
	public static void Main()
	{
	  //Change these three variables to decode your own; need a key and IV to decode!
		string ciphertext = "BQO5l5Kj9MdErXx6Q6AGOw==";
		string key = "c4scadek3y654321";
		string iv = "1tdyjCbY1Ix49842";
		
		string plaintext = string.Empty;
		plaintext = DecryptString(ciphertext, key, iv);
		Console.WriteLine(plaintext);
	}
	
	public static string DecryptString(string EncryptedString, string Key, string iv)
    {
      byte[] buffer = Convert.FromBase64String(EncryptedString);
      Aes aes = Aes.Create();
      ((SymmetricAlgorithm) aes).KeySize = 128;
      ((SymmetricAlgorithm) aes).BlockSize = 128;
      ((SymmetricAlgorithm) aes).IV = Encoding.UTF8.GetBytes(iv);
      ((SymmetricAlgorithm) aes).Mode = CipherMode.CBC;
      ((SymmetricAlgorithm) aes).Key = Encoding.UTF8.GetBytes(Key);
      using (MemoryStream memoryStream = new MemoryStream(buffer))
      {
        using (CryptoStream cryptoStream = new CryptoStream((Stream) memoryStream, ((SymmetricAlgorithm) aes).CreateDecryptor(), CryptoStreamMode.Read))
        {
          byte[] numArray = new byte[checked (buffer.Length - 1 + 1)]; //not sure why this has -1+1 here, example works without it though...
          cryptoStream.Read(numArray, 0, numArray.Length);
          return Encoding.UTF8.GetString(numArray);
        }
      }
    }
}

Decodes to: w3lc0meFr31nd

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