Authorities have not yet identified the hacker behind the Panama Papers breach, nor have they isolated the exact attack vector. It is clear that Mossack Fonseca, the Panamanian law firm that protected the assets of the rich and powerful by setting up shell companies, had employed a dangerously loose policy towards web security and communications.

The firm ran its unencrypted emails through an outdated (2009) version of Microsoft’s Outlook Web Access. Outdated open source software running the frontend of the firm’s websites is also now suspected to have provided a vector for the compromise.

In initial communications with German newspaper the Süddeutsche Zeitung (SZ), an anonymous source offered the data with a few conditions, saying that his/her life was in danger.

“How much data are we talking about?” the SZ asked.

“More than anything you have ever seen,” the source said.

The Panama Papers breach is the largest data leak in history by a wide margin, with 2.6 terabytes of data, 11.5 million documents, and more than 214,000 shell companies exposed.

Forbes has identified outdated WordPress and Drupal installations as security holes that may have led to the data leak.

Forbes discovered the firm ran a three-month-old version of WordPress for its main site, known to contain some vulnerabilities, but more worrisome was that, according to Internet records, its portal used by customers to access sensitive data was most likely run on a three-year-old version of Drupal, 7.23.

This information is partially inaccurate, however. While looking at the site today, I found that the firm’s WordPress-powered site is currently running on version 4.1 (released in December 2014), based on its version of autosave.js, which is identical to the autosave.js file shipped in 4.1. Since that time WordPress has had numerous critical security updates.

The main site is also loading a number of outdated scripts and plugins. Its active theme is a three-year-old version of Twenty Eleven (1.5), which oddly resides in a directory labeled for /twentyten/.

The Mossack Fonseca client portal changelog.txt file is public, showing that its Drupal installation hasn’t been updated for three years. Since the release of version 7.23, the software has received 25 security updates, which means that the version it is running includes highly critical known vulnerabilities that could have given the hacker access to the server. This includes a 2014 SQL injection vulnerability known in the Drupal community as “Drupalgeddon,” which affected every site running Drupal 7.31 or below.

Investigators have not confirmed if the open source software vulnerabilities were used to access the data, but it is certainly plausible given the severity of the vulnerabilities in both older versions of WordPress and Drupal.

“They seem to have been caught in a time warp,” Professor Alan Woodward, a computer security expert from Surrey University, told WIRED UK. “If I were a client of theirs I’d be very concerned that they were communicating using such outdated technology.”

If these open source software vulnerabilities provided the access point for this massive leak, then this company’s global fiasco was entirely preventable. Although many people welcome the uncovering of corruption and dirty money transactions of famous people and world leaders, the reality is that these kinds of exploits can also be carried out on well-meaning organizations that exist to protect people’s health records, financial data, and other sensitive information.

This leak is not a measure of open source software’s reliability but rather underscores how low a priority some companies place on their tech departments and web security. With the rampant software vulnerabilities in this age, not updating software for years constitutes abject neglect of customers.

The bottom line is that software needs to be updated. This kind of routine maintenance is as foundational to a company’s business as brushing teeth or showering is for one’s health. Law firms and companies with such a lax approach to security are either ignorant or unwilling to spend the money to maintain technology that they don’t fully understand. The Panama Papers serve as a reminder that having a competent, skilled tech department is critical for any company that deals in sensitive information.