Jack, a system administrator at company XYZ, has discovered some new files that were added to one of his servers. One of the files contained programming code; after thorough examination of the code…

Jack, a system administrator at company XYZ, has discovered some new files that were added to one of his servers. One of the files contained programming code; after thorough examination of the code it was discovered that it was purposely built to take advantage of a known weakness on the system. What would you call this piece of code?