Anybody who watched Facebook CEO Mark Zuckerberg's tedious multiday testimony before Congress earlier this month might recall a particularly heated segment during the second day of hearings where one Congressman harangued Zuckerberg about illegal opioids being openly sold on Facebook's platform.

At the time, Zuckerberg promised the lawmaker that Facebook would remove the offending posts down as soon as they were flagged. But he was unable to offer a definitive promise that Facebook would be able to stamp out drug dealing on its platform entirely - though he added that the company's AI tools for filtering posts that violate its terms of service are constantly improving, and that the company was in the process of hiring thousands of employees who would help screen content.

But apparently, the opioid sales were only the tip of the iceberg.

As a blockbuster report published by Motherboard on Tuesday revealed, cyber criminals have been posting sensitive personal information including credit card numbers and social security numbers on Facebook, and some of these posts remained on the social network for years. Others were taken down as soon as Motherboard notified Facebook of their presence.

Cybercriminals have posted sensitive personal information, such as credit card and social security numbers, of dozens of people on Facebook and have advertised entire databases of private information on the social platform. Some of these posts have been left up on Facebook for years, and the internet giant only acted on these posts after we told it about them.

... Most of the posts appeared to be ads made by criminals who were trying to sell personal information. Some of the ads are several years old, and were posted as "public" on Facebook, meaning anyone can see them, not just the author’s friends. Independent security researcher Justin Shafer alerted Motherboard to these posts Monday. "I am surprised how old some of the posts are and that it seems Facebook doesn’t have a system in place for removing these posts on their own," Shafer told Motherboard in an online chat. "Posts that would have words flagged automatically by their system."

And what's worse, rather than being buried somewhere on the dark web, the sales listings were easily found on Facebook's platform after a simple Google search, as Motherboard demonstrated...

Zuckerberg advised during his testimony that changes to how Facebook monetizes user data would have a "significant impact" on the company's bottom line - though he's also insisted that any impact from the scandal has been negligible (despite surveys showing a drop off in usage rates).

Meanwhile, even as most hedge funds are again getting slammed on today's stock drop, at least one person is making money on the news: yesterday, Jeffrey Gundlach unveiled his Ira Sohn trade reco: go long oil, and short Facebook, arguing that Zuckerberg's apology sounded disingenuous and that "one more scandal could inspire lawmakers to pass restrictive regulations that could seriously harm Facebook's profitability."

This could be just that scandal.

Facebook shares were down nearly 4% in early afternoon trading as the recent dead cat bounce now appears to be over: