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Because base64 converts from an 8 bit to a 6 bit character system, you can get 3 unique base64 strings from a single ascii string depending on the position of the first character.
for example:
base64_encode("system");
base64_encode(" system");
base64_encode("( system");
The above 3 input strings all produce very different base64 signatures even though they all contain the same keyword 'system'. This is because the first letter of system, 's' fall on indices 0,1,2 respectively.
I updated several of the base64 samples to include their offset counterparts as the originals would only catch about 1 in 3 of the actual present matches.
PHP malware scanner
Traversing directories for files with php extensions and testing files against text or regexp rules, the rules based on self gathered samples and publicly vailable malwares/webshells. The goal is to find infected files and fight against kiddies, because to easy to bypass rules.
How to use?
$ php ./scan.php -h
Usage scan.php -d <directory> [-i=<directory|file>] [-e=.php] [--hide-ok] [--hide-whitelist]
-d Directory for searching
-e=.php Extension
-i=<directory|file> Directory of file to igonre
--hide-ok Hide OK aka not infected messages
--hide-whitelist Hide whitelisted messages
--extra-check Adds GoogleBot and htaccess to Scan List
--follow-symlink Follow symlinked directories
Ignore argument could be used multiple times and accept glob style matching ex.: "cache*", "??-cache.php" or "/cache" etc.
Patterns
There are two different pattern source, each line in these files is a patter so patterns_raw.txt lines searched as-is, patterns_re.txt used with preg_match function.
Whitelisting
See whitelist.txt file for a predefined MD5 hash list. Only the first 32 characters are used, rest of the line ignored so feel free to leave a comment.
Resources
- PHPScanner
- PMF - PHP Malware Finder
- check regexp online
- malware samples 1
- malware samples 2
- malware samples 3
- malware samples 4
Licensing
PHP malware scanner is licensed under the GNU General Public License v3.