Revealed in September 2013 by a joint ProPublica, New York Times, and Guardian investigation using Snowden documents, Bullrun was a classified NSA programme to covertly undermine encryption standards, introduce backdoors into commercial products, and work with or coerce technology companies to weaken their cryptographic implementations. The most specific confirmed element was the NSA's role in promoting Dual_EC_DRBG as an NIST standard with a likely built-in backdoor. A December 2013 Reuters report revealed that RSA Security had received $10 million from the NSA to make Dual_EC the default random number generator in its BSAFE toolkit.