sysrandom | Secure random number generation for Ruby using system RNG | Cryptography library

The version of metasploit you linked to doesn't appear to have been updated in a few years. It doesn't list sysrandom as a dependency in the Gemfile.

There's a newer version which does have sysrandom as a dependency, here:

https://github.com/rapid7/metasploit-framework/blob/master/metasploit-framework.gemspec#L106

I'm not sure why pentestbox is using such an old version, but I'm assuming the "update" actually updates to the rapid7 version of metasploit (because it's looking for sysrandom which only exists there).

There are a few things you can try:

• bundle install should install all the dependencies (without using the console tool built for pentestbox)
• Deleting the Gemfile.lock and running bundle install. I don't usually recommend this but if there seems to be a version mismatch somewhere and sometimes this resolves dependencies errors. You should be able to re-check this file out again (assuming it's versioned locally)

If you can post the git commit hash of the metasploit version you've downloaded that might help provide additional suggestions for resolving.