It's a sad reality in 2017 that a data breach affecting 143 million people is dwarfed by other recent hacks—for instance, the ones hitting Yahoo in 2013 and 2014, which exposed personal details for 1 billion and 500 million users respectively; another that revealed account details for 412 million accounts on sex and swinger community site AdultFriendFinder last year; and an eBay hack in 2014 that spilled sensitive data for 145 million users.

The breach Equifax reported Thursday , however, very possibly is the most severe of all for a simple reason: the breath-taking amount of highly sensitive data it handed over to criminals. By providing full names, Social Security numbers, birth dates, addresses, and, in some cases, driver license numbers, it provided most of the information banks, insurance companies, and other businesses use to confirm consumers are who they claim to be. The theft, by criminals who exploited a security flaw on the Equifax website, opens the troubling prospect the data is now in the hands of hostile governments, criminal gangs, or both and will remain so indefinitely.

Hacks hitting Yahoo and other sites, by contrast, may have breached more accounts, but the severity of the personal data was generally more limited. And in most cases the damage could be contained by changing a password or getting a new credit card number.

What's more, the 143 million US people Equifax said were potentially affected accounts for roughly 44 percent of the population. When children and people without credit histories are removed, the proportion becomes even bigger. That means well more than half of all US residents who rely the most on bank loans and credit cards are now at a significantly higher risk of fraud and will remain so for years to come. Besides being used to take out loans in other people's names, the data could be abused by hostile governments to, say, tease out new information about people with security clearances, especially in light of the 2015 hack on the US Office of Personnel Management, which exposed highly sensitive data on 3.2 million federal employees, both current and retired.

Amateur response

Besides the severity and scope of the pilfered data, the Equifax breach also stands out for the way the company has handled the breach once it was discovered. For one thing, it took the Atlanta-based company more than five weeks to disclose the data loss. Even worse, according to Bloomberg News, three Equifax executives were permitted to sell more than $1.8 million worth of stock in the days following the July 29 discovery of the breach. While Equifax officials told the news service the employees hadn't been informed of the breach at the time of the sale, the transaction at a minimum gives the wrong appearance and suggests incident responders didn't move fast enough to contain damage in the days after a potentially catastrophic hack came into focus.

What's more, the website www.equifaxsecurity2017.com/, which Equifax created to notify people of the breach, is highly problematic for a variety of reasons. It runs on a stock installation WordPress, a content management system that doesn't provide the enterprise-grade security required for a site that asks people to provide their last name and all but three digits of their Social Security number. The TLS certificate doesn't perform proper revocation checks. Worse still, the domain name isn't registered to Equifax, and its format looks like precisely the kind of thing a criminal operation might use to steal people's details. It's no surprise that Cisco-owned Open DNS was blocking access to the site and warning it was a suspected phishing threat. (Update: The whois records were updated on Sunday and now show the domain is registered to Equifax.)

Another indications of sloppiness: a username for administering the site has been left in a page that was hosted here. Here's what it looked like before it was taken down at about 8:50 am California time:

That by itself wouldn't allow for unauthorized access, but it's still something that should never have happened.

Meanwhile, in the hours immediately following the breach disclosure, the main Equifax website was displaying debug codes, which for security reasons, is something that should never happen on any production server, especially one that is a server or two away from so much sensitive data. A mistake this serious does little to instill confidence company engineers have hardened the site against future devastating attacks.

It was bad enough that Equifax operated a website that criminals could exploit to leak so much sensitive data. That, combined with the sheer volume and sensitivity of the data spilled, was enough to make this among the worst data breaches ever. The haphazard response all but guarantees it.

Post updated to add details about exposure of user name.