Can the government get a full picture of who you are by friending you on Facebook and monitoring your friends and family? The Department of Homeland Security thinks so, and is apparently willing to pose as that hot girl next door in order to become your friend.

The Electronic Frontier Foundation recently got its hands on a DHS document titled "Social Networking Sites and Their Importance to FDNS" (PDF) as part of its work on social network surveillance. The document generally details how social networks function and provides a list of popular sites that people around the world like to use, including Facebook, Badoo, Imeem, MySpace, Windows Live Spaces, and others.

However, the document also highlights to agents the importance of amassing a lengthy friend list to many social network users, and how they can take advantage of it. "Narcissistic tendencies in many people fuels a need to have a large group of 'friends' link to their pages and many of these people accept cyber-friends that they don’t even know," reads the document. "This provides an excellent vantage point for FDNS to observe the daily life of beneficiaries and petitioners who are suspected of fraudulent activities."

Agents are encouraged to take the opportunity to reveal fraud by poking around in people's profiles to see whether they are in valid relationships or are attempting some other kind of fraud to get into the country. "Once a user posts online, they create a public record and timeline of their activities. In essence, using MySpace and other like sites is akin to doing an unannounced cyber “site-visit” on a [sic] petitioners and beneficiaries," instructs the DHS.

As noted by the EFF, the memo doesn't require DHS agents to reveal their government affiliation (or even their real names) before sending friend requests, nor does it specify what level of suspicion agents must have before trying to friend someone for surveillance.

On top of this, the DHS also monitored (PDF) a number of social networks for "items of interest" in the months leading up to President Obama's inauguration in 2009. In addition to the usual suspects (Facebook, MySpace, Twitter, YouTube, Digg, Blogger, Craigslist, Wikipedia, and Flickr), the DHS also monitored the sites for certain demographic groups, such as MiGente and Black Planet, as well as NPR and DailyKos.

Although the document emphasizes that personally identifiable information shouldn't be collected, it later says that anything publicly divulged is open season for further analysis.

The EFF sharply criticizes the government for its data collection on citizens and non-citizens alike, as well as its apparent opaqueness when it comes to friending people online. The one major lesson for users, however, is to always be skeptical of friend requests from people you don't know. Is your online privacy worth the tradeoff for one more mark on the nightstand? As senior editor Nate Anderson pointed out while discussing this piece, there are apparently benefits to being a Facebook curmudgeon after all.