In such a scenario, I believe the best thing to do is to avoid certain mistakes and remain focused and very careful on your job so that your colleagues or people who don't mean you well in your office don't find anything tangible that can be used against you.
It is also important to remain faithful by being truthful and doing our work activities diligently at all times has this will safe you greatly into falling into some of their traps. Every situation presents an opportunity for us to shine brighter, we ought to take certain attacks to our favor instead of allowing it to consume us.
Taking them head on by countering them will not do much as they outweigh you. Minding your business when it comes to work at all times should be the mindset in which all things are channeled into. Been introverted doesn't mean we also willing allow them to oppress us or back us into a corner. We should stand our ground no matter the oppression that befall us and not back down or give them any advantage. If we continue this way, they will be forced to quit or abandon their wicked plans concerning you.