Besides namespaces, if one were malicious, one could also hide loaded libraries from lsof another way: open the library file, memcpy() the contents into RAM som

Besides namespaces, if one were malicious, one could also hide loaded libraries from lsof another way: open the library file, memcpy() the contents into RAM somewhere, mprotect(...,PROT_EXEC) that contents and then close the library file. You'll have to do your own linking, but then no open file will appear except for a very brief moment.