The three answers above are all great ideas. But I'd like to expand on two of these answers with a story from my own personal experience in finding what to do for research.
If you're in the early stages of research but you're not that passionate about it, I would suggest looking for other research opportunities that inspire more passion. You may not want to switch your current focus or advisor (and at first, I didn't either), but it may very well be useful for you to explore, just to see if there might be some other arrangement that better motivates you.
In short, you might try the following:
- find some aspect of life that you're very passionate about
- see if you can find some research project in your field that speaks to your passion
- find an advisor who is willing to work with you on such a project, and who fits your personality well enough for you to work with this person in an effective manner.
While cloudraven suggests to look for specific problems, I'd take it a step back from that and say that you should first look for a topic of study that speaks to a passion of yours, even if that topic is not itself within computer science. First, it may not be obvious if you can connect it with your current field of study. However, you may be surprised at the ways people have studied this topic using computer science, or the ways in which people are motivated to study some aspect of computer science because of this topic. Then, once you've linked that passion to your field of study, it may not immediately be obvious what problems are still open that you can attack. This is fine - it will require some hard work to find a specific research path, and moreover formulating your own thesis problem will likely require a lot of help from an advisor.
(Disclaimer: I'm an applied math grad student, so admittedly I may very well have a wider range of possibilities for research than students in other fields. Thus, taking a general life passion and researching it may well be easier for me than for you. However, computer science and applied math share a substantial overlap, so this advice may be somewhat relevant.)
I had been working on a project with a very interesting theoretical aspect, but the physical application did not quite excite me enough to provide the drive I needed to get anywhere on my research. Also, I was working with a well-respected and talented advisor, but we didn't meet or communicate very often. This was in part because that year he was teaching and researching at another university, but also because he had a lot of students and was otherwise busy with work. In any case, I became his student under a mutual understanding between us that I would work in a very independent fashion. While at first I thought that such an arrangement was perfect for me, it gradually became more obvious that I needed more frequent, in-person meetings to stay motivated.
And then I took a class on applied and harmonic computational analysis, a topic which is very much related to the field of music technology. I've always been a very musical person, and it's a really big passion for me. But I didn't realize that I could connect this passion with my field of study until I did a small research project for that class. People talk all the time about how music and math are related, but I never really heard much of people doing applied math projects that involved music until I actually went out myself and looked for these topics.
(If you want to hear what the problem was that motivated me, well... I wanted to make a remix of a song, but I couldn't separate out the vocal track as I wanted. Eventually, this led me to discover the topic of source separation, which arises in not just music technology but also a surprising number of academic disciplines. From there, I started discovering many other different topics that I find to be pretty cool.)
Since then, I've switched advisors and started some really fun, exciting projects. And I'm no longer nearly as worried as I used to be about whether I'm making enough progress, not only because of my passion for my project, but also because I check in weekly with my advisor.