How do I get into a top university like UPenn, UCLA, or Brown for a Master's in Computer Science coming from a foreign university?

If you're coming with a degree from a foreign university, make sure that your degree is considered the equivalent in the US....The standards between countries are not always the same....Make sure you've taken the the equivalent number of credit hours, similar classes, etc.

Yes of course it is possible. I am assuming that the admission committee would most likely have never heard of your school. You need to show one or more of these things (not an exhaustive list by means) - You are among the top students of your university in terms of academic performance. Something like a rank in top 5. You should have good letters of recommendations. Although I am not really sure how much they are valued for master's admissions. It would greatly help your case if you have a publication or two in a reputed conference or a journal. If you relevant work experience in a reputed company which the admission committee might know of. The whole point is that you must be able to verify your credibility to them in some way or another. For example if you have a medal in some international Olympiad or a prize in an international event ( just an example), then that would greatly help your case.

In short : YES ! Now, the long answer. As a recent MS graduate from UPenn who did her undergraduate studies in India, I would like to highlight a few points, which (in my opinion) help.  1. Have a strong SOP (Statement of Purpose). It is a deal breaker. I am surprised this has not been mentioned yet. For international students, SOP is the only way you can make the admission committee understand you.  Make your SOP clear, cohesive and concise. And if you can convince them about the following 2 points, half your battle is won . (A) Why you want to attend (your previous research experiences, grades, LORs confirming your capabilities) (B) What can you bring to the table (Your plan of action after you join - professors/projects you want to work on, your short and long term goals during and post MS) 2. Get honest LORs (Letter of recommendations) from people who have worked with you or known you for a long time. Out of 3 LORs, at least 1 of them should be of this type. The admissions committee is trying to understand you - and a person who knows you well , even though she/he might not be well known - is a good bet for a LOR. 3. Apply early - Some universities have rolling admissions (UPenn does) . The earlier you apply, the better are your chances for being given thorough consideration. Its all about convincing the committee that an admit to you is worth the efforts. Make sure you 'grammar and spell check' all your documents - if required get some professor or writer to review your essays. And, like mentioned by others, keep your grades and GRE, TOEFL scores at their highest. All the best :)