Your best source of information on all Federal Benefits overseas can be found at http://travel.state.gov/travel/living/living_1234.html
The Consulate does not process claims for Social Security, but can assist you with forms and other information. You may also wish to visit the Social Security Administration's website at http://www.ssa.gov The nearest Social Security Administration office, serving East and South Asia (including Pakistan) is located at the U.S. Embassy in Manila, Philippines.
You can contact them directly as follows:
Social Security Administration
U.S. Office Building
1131 Roxas Boulevard