This exploit finds the HMAC secret key used in Java serialization by Apache Tapestry. This key is located in the file AppModule.class by default and looks like the standard representation of UUID in hex digits (hd) : 6hd-4hd-4hd-4hd-12hd If the HMAC key has been changed to look differently, this module won't find the key because it tries to download the file and then uses a specific regex to find the key.
To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':
msf > use auxiliary/gather/cve_2021_27850_apache_tapestry_hmac_key
msf auxiliary(cve_2021_27850_apache_tapestry_hmac_key) > show actions
...actions...
msf auxiliary(cve_2021_27850_apache_tapestry_hmac_key) > set ACTION < action-name >
msf auxiliary(cve_2021_27850_apache_tapestry_hmac_key) > show options
...show and set options...
msf auxiliary(cve_2021_27850_apache_tapestry_hmac_key) > run
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