It sounds an awful lot like that's the one the New York times was describing. Can you think of any other standard that was published in 2006 by NIST which two Microsoft researchers discovered a flaw in in 2007? That sounds exactly like Dual_EC_DRBG
> Simultaneously, the N.S.A. has been deliberately weakening the international encryption standards adopted by developers. One goal in the agency’s 2013 budget request was to “influence policies, standards and specifications for commercial public key technologies,” the most common encryption method.
> Cryptographers have long suspected that the agency planted vulnerabilities in a standard adopted in 2006 by the National Institute of Standards and Technology, the United States’ encryption standards body, and later by the International Organization for Standardization, which has 163 countries as members.
> Classified N.S.A. memos appear to confirm that the fatal weakness, discovered by two Microsoft cryptographers in 2007, was engineered by the agency. The N.S.A. wrote the standard and aggressively pushed it on the international group, privately calling the effort “a challenge in finesse.”
> “Eventually, N.S.A. became the sole editor,” the memo says.
Now, that may not have been an effective technique, as you point out it's so slow that no one is ever going to use it, and this vulnerability was discovered not long after it was published.
So, that's obviously not a vulnerability that they are actively exploiting. If they are actively exploiting a vulnerability that they introduced, it must be something else. It wasn't clear from the article that that's actually the case; it may be that the vulnerabilities they are exploiting are ones they've found, not introduced deliberately.
But it does appear to be an example of a vulnerability that they were able to get standardized, in the hopes of being able to exploit it. Until now, it has been only speculation that it was a deliberate vulnerability, but it now seems clear that it was.