These PDF editors are functional but each contain a backdoor
https://virustotal.com/gui/file/fde67ba523b2c1e517d679ad4eaf87925c6bbf2f171b9212462dc9a855faa34b
https://bazaar.abuse.ch/sample/17355179730a16c9a1e4e81b747ae084618c2210c11dcb78b291ca757dacc853/
URLs
pdfreplace(dot)com
pdfmeta(dot)com
pdfartisan(dot)com
appsuites(dot)ai