Comment 0 for bug 1808882

This has apparently been a thing since at least 16.04

Install a clean version of Ubuntu, install chkrootkit, run a check.

tcpd will report as infected.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: chkrootkit 0.52-1
ProcVersionSignature: Ubuntu 4.15.0-42.45-lowlatency 4.15.18
Uname: Linux 4.15.0-42-lowlatency x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: MATE
Date: Mon Dec 17 18:30:29 2018
InstallationDate: Installed on 2018-12-05 (12 days ago)
InstallationMedia: Ubuntu-MATE 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: chkrootkit
UpgradeStatus: No upgrade log present (probably fresh install)