  In this work we attempt to overcharge extremal and nearly extremal charged
black holes in string theory, known as the Garfinkle-Horowitz-Strominger
solution. We first show that extremal black holes cannot be overcharged
analogous to the case of Reissner-Nordstr\"{o}m black holes. Contrary to their
analogues in general relativity, nearly extremal black holes can neither be
overcharged beyond extremality, nor can they be driven to extremality by the
interaction with test particles. Therefore the analysis in this work also imply
that the third law of black hole thermodynamics holds for the relevant charged
black holes in string theory perturbed by test particles. This can be
interpreted as a stronger version of the third law since one can drop out the
continuity proviso for the relevant process.
