No its not malware its an important Unix code and repository for binaries and daemons for a range of MacOS and other Unix service extensions
There is a lot of misinformation out there, because there is a similarly named trojan that is used to insert adware in browsers and java based apps via daemon scripts.
Libexec not the problem; rather the likes of Norton security software is that erroneously reports it presence as a threat.
Best path is REMOVE Norton not this important standard Unix binary
Norton does more harm than good on MacOS
It can't easily be removed in anyway as its read only.