The NSA bought specialist computer hacking tools and research from French security outfit Vupen, according to documents unearthed using the Freedom of Information Act.
A contract shows the American spooks paid for a year's supply of zero-day vulnerability information and the software needed to exploit those flaws to attack electronic systems.
The paperwork, obtained by government transparency and accountability site MuckRock, show that the US intelligence nerve-centre signed up to a one-year subscription to Vupen's “binary analysis and exploits service” last September.
Vupen prides itself on advanced vulnerability research as well as selling software exploits for unpatched flaws in systems - known as zero-days - to governments. Several US defence contractors and security startups, such as Endgame Systems, are also in the business of privately researching and selling information about software vulnerabilities and associated attack code.
That US government organisations may be among Vupen's customers is not a surprise. The NSA, even though it has advanced offensive cybersecurity capabilities, not least in the shape of its Tailored Access Operations cyber-espionage unit, might still find it valuable to tap into external help from commercial providers such as Vupen.
"Likely reasons for NSA subscription to Vupen's 0day exploits: know what capabilities other govs can buy, and false flag, deniable cyber-ops," writes Christopher Soghoian, principal technologist and senior policy analyst at the American Civil Liberties Union in an update to his personal Twitter account.
"There are times when US special forces use AK47s, even though they have superior guns available. Same for NSA's Vupen purchase. Deniability," he added.
Soghoian, who delivered a presentation about the exploit vulnerability marketplace at the recent Virus Bulletin conference, has previously likened the trade in software exploits to a trade in conventional weapons - think bullets, bombs and rockets. ®