- tl;dr Version -
How did information of Section 9's involvement with the second kidnapping of Mr. Serano, which happened in episode 23 of GitS:SAC, get leaked to the media? I can't find any source online that clarifies this.
- Longer Version -
In episode 23 of GitS:SAC, Major Kusanagi uses the memories she obtained from the Laughing Man to stage a second kidnapping of Mr. Serano under the guise of the Laughing Man himself in order to verify the connection between Serano Genomics and Secretary General Yakushima. During the kidnapping, Major Kusanagi impersonated the Laughing Man perfectly because, well, she was the Laughing Man for all intents and purposes. However, the degree to which the rest of Section 9 was filled in on this plot seems to be vague. Throughout the episode you can see the rest of Section 9 trying hard to "arrest the laughing man", though it's conceivable that this could have all been part of Section 9's plan.
Regardless of whether or not the rest of Section 9 was filled in on this plan, how on earth did the media find out that it was the Major who impersonated the Laughing Man and kidnapped Mr. Serano? At most only the members of Section 9 knew about this (and possibly the Laughing Man himself I suppose), so who leaked the information? One possibility is that Major's girly eyes gave it away, as is slightly indicated at the beginning of episode 24 when Chief Aramaki and Togusa are in the car, but that seems like a silly way for the news to be leaked. In the GitS:SAC wiki page, it's claimed that Secretary General Yakushima, the guy who this entire Laughing Man plot is focused on putting to justice, found out that Section 9 was behind the kidnapping and so leaked that info to the media (which played a very big role in the rest of the story). But how would Yakushima have known about that? Who told him?
What's really weird about all this is that in the beginning of episode 24, Chief Aramaki tells nearly everybody in Section 9 to "find out where news of our op was leaked from." But nobody ever seems to give an answer to this!