This 19-page NSA paper, delivered at the 2010 Five Eyes SIGDEV conference, gives a technical explanation of the importance of sourcing mobile carriers’ roaming agreements (IR.21): see the Intercept article Operation Auroragold: How the NSA Hacks Cellphone Networks Worldwide, 4 December 2014. ir21-a-technology-warning-mechanism

This 26-page NSA document, originally presented at 2012’s Five Eyes SIGDEV conference, gives a detailed overview of the agency’s information gathering on world mobile phone networks. Some intercepted technical and contact details have been redacted: see the Intercept article Operation Auroragold: How the NSA Hacks Cellphone Networks Worldwide, 4 December 2014.

This undated NSA presentation describes techniques for detecting botnets: see the Der Spiegel article The Digital Arms Race: NSA Preps America for Future Battle, 17 January 2015.

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.