Intelligence agencies are very careful about sharing their findings, even with "friends", because the findings will disclose some information about their capabi

Intelligence agencies are very careful about sharing their findings, even with "friends", because the findings will disclose some information about their capabilities and possibly methods. Let's say agency A has some scanning capability on open source software that detected this backdoor attempt by agency B. If they had gone public, agency B now knows they have this ability. So agency B will adjust their ways the next time and the scanning capability becomes less useful. While if agency A had told Microsoft to "find" this by accident, nobody would know about their scanning capability. And the next attempt by agency B would only try to avoid having the performance impact this first attempt had, probably leaving it visible to agency A.