“The 30-year-old’s role as a ‘system administrator‘ meant that he was able to access NSAnet, the agency’s intranet, using those user profiles and without leaving any signature. An official told NBC that the NSA identified several instances in which the elite NSA-trained hacker impersonated officials, and that the spy agency’s forensic investigation is ‘trying to figure out which higher level officials Snowden impersonated online to access the most sensitive documents.’ Last week Michael Isikoff, Cole, and Esposito reported that the NSA is ‘overwhelmed’ – does not know the full extent of the tens of thousands of documents the former NSA contractor took from its system.”
http://www.businessinsider.com/snowden-digitally-impersonated-nsa-officials-2013-8