Caveat poster: A security researcher has assembled a single database containing 35 million people's Google Profiles information, including Twitter feeds, real names, and email addresses, among other data points.

Google bills Profiles as a way to "decide what the world sees when it searches for you."

But Matthijs R. Koot, a privacy and anonymity researcher at the University of Amsterdam, also found that because of the nature of Google Profiles--it's meant to be indexed by search engines--he was able to easily save available information into a SQL database. Doing so required about a month's effort "to retrieve the data, convert it to SQL using spidermonkey and some custom Javascript code, and import it into a database," he said in a blog post.

The resulting database contains whatever people have added to their own Google Profile, which potentially includes their real name, aliases, Twitter conversations, work experience and educational background, and links to Picasa photos. In addition, Koot said that about 15 million profiles also have a username, which is the same as a person's Gmail address. Interestingly, Koot said that he was able to assemble the data "without Google throttling, blocking, CAPTCHAing" or encountering any other form of security protection.

The potential threat, or nuisance, posed by Google Profiles has to do with social engineering attacks and marketing firm practices. Namely, savvy attackers would have access to extensive amounts of personal information, which they could use to help make phishing or targeted attacks appear more realistic. Likewise, marketing firms have more information available for targeting potential customers. This threat, challenge, or--depending on your perspective--business opportunity isn't new. What is new, however, is the sheer amount of personal information that's easily available in one go.

According to a recent, global study, Internet users typically have an online expectation of privacy. But as Koot's project demonstrates, the reality can be different. Notably, third-party advertisers and affiliates can collect extensive amounts of personal information.

Koot said as much when explaining his rationale for this project. "My activities are directed at inciting, or poking up, debate about privacy--not to create distrust but to achieve realistic trust--and the meaning of 'informed consent.' Which, when signing up for online services like Google Profile, amounts to checking a box." The value of research such as Koot's project is also to illustrate not just what's possible, but what--from a marketing, advertising, or social engineering perspective--has probably already been done.

Koot's work recalls a similar project conducted in July 2010 by Ron Bowes, a security researcher and developer at Tenable Network Security, only with Facebook. Notably, thanks to Facebook's directory, Bowes was able to build a script that harvested 171 million Facebook usernames, 100 million of which were unique, as well as the URL for each profile. (Gathering more names may also have been possible, with tweaks for non-Romance-language alphabets.) Bowes published the information he'd gathered as a torrent file.

"This is a scary privacy issue," he said in a blog post at the time. "I can find the name of pretty much every person on Facebook. Facebook helpfully informs you that "[a]nyone can opt out of appearing here by changing their search privacy settings"--but that doesn't help much anymore considering I already have them all (and you will too, when you download the torrent)."

In this new Tech Center report, we profile five database breaches--and extract the lessons to be learned from each. Plus: A rundown of six technologies to reduce your risk. Download it here (registration required).