Wordpress theme checker plugins are used to find any malicious code in your wordpress theme.
Theme-check wordpreess plugin is used to test your theme with the latest theme review standards from wordpress. To know more about wordpress theme review standards click here .
The tests are run through a simple admin menu.
TAC (Theme Authenticity Checker)
TAC Scans the source files of every installed theme files for potentially malicious or unwanted code and it displays the path to the theme file, the line number, and snippet of code.