This is a problem; normal matter in space will heat up until it gives off light, so if this missing mass exists, it is generally assumed to be in a form that is not commonly observed on earth.
Early candidates included heavy baryons that would have had to be created in the Big Bang, but more recent work on nucleosynthesis seems to have ruled most of these out.
The CDMS detectors measure the ionization and phonons produced by every particle interaction in their germanium and silicon crystal substrates.
[1] These two measurements determine the energy deposited in the crystal in each interaction, but also give information about what kind of particle caused the event.
This allows WIMP-scattering events to be identified even though they are rare compared to the vast majority of unwanted background interactions.
The extremely low temperatures are needed to limit thermal noise which would otherwise obscure the phonon signals of particle interactions.
CDMS detectors also provide data on the phonon pulse shape which is crucial in rejecting near-surface background events.
Due to the low number of events, the team could exclude false positives from background noise such as neutron collisions.
Their limits rule out hints claimed by a new germanium experiment called CoGeNT and the long-standing DAMA/NaI, DAMA/LIBRA annual modulation result.
SuperCDMS search results from October 2012 to June 2013 were published in June 2014, finding 11 events in the signal region for WIMP mass less than 30 GeV, and set an upper limit for spin-independent cross section disfavoring a recent CoGeNT low mass signal.
GEODM (GErmanium Observatory for Dark Matter), with roughly 1500 kg of detector mass, has expressed interest in the SNOLAB "Cryopit" location.
The purpose of building in ten-fold stages like this is to develop the necessary shielding techniques before finalizing the GEODM design.