XF 1.5 vbseo attachment mod_rewrite rule

[island]

I'm trying to redirect
mydomain.com/forums/attachments/forumname/967069d1386487532-filename-with-numbers-in-itself-540-maybe-another-number-540-small.pdf

Where the attachmentID is 967069d1386487532

AttachmentID follows a / and is followed by a -

Can anyone help me with a rewrite rule? (apache)

 

[island]

Not sure if this is possible.

Thinking about this, I would either need to

"search" backward from the end of the filename to the first / encountered right to left, and then include the string to the first - left to right
following that,

or I would need to

skip content until 4 / are present, and then include the string to the first - encountered after that.

Has anyone done this?