This undated NSA presentation describes how to perform attacks against VPNs: see the Der Spiegel story Prying Eyes: Inside the NSA’s War on Internet Security, 28 December 2014.
These three undated NSA slides provide an overview of the VALIANTSURF system: see the Der Spiegel story Prying Eyes: Inside the NSA’s War on Internet Security, 28 December 2014.
This undated presentation from NSA’s Network Analysis Center describes agency techniques for overcoming Virtual Private Networks (VPNs): see the Der Spiegel story Prying Eyes: Inside the NSA’s War on Internet Security, 28 December 2014.
This undated NSA document gives updates on various activities of the US-German Joint SIGINT Activity during 2007: see the Der Spiegel article Snowden-Dokumente: Hier sitzt die NSA in Deutschland, 18 June 2014.
This internal NSA report dated 14 August 2009 describes that year’s SIGDEV (Sigint Development) Conference, in which representatives of 5 Eyes agencies and the wider US intelligence community meet “to synchronize discovery efforts, share breakthroughs, and swap knowledge on the art of analysis”: see the Intercept article: The “Cuban Twitter” Scam Is a Drop in the Internet Propaganda Bucket, 4 April 2014.
This short extract from an April 2011 NSA document describes the operation of the agency’s QUANTUMHAND tool: see the Intercept article Compare the NSA’s Facebook Malware Denial to its Own Secret Documents, 15 March 2014.