The FBI warned this week that Anonymous hackers — a loosely connected faction of computer hacker activists — managed to breach U.S. government computers over the course of the last year, gaining access to a plethora of sensitive information from a variety of government agencies.

According to the FBI, the Anonymous hackers group exploited a flaw in Adobe Systems Inc's software from which they launched a wide range of electronic attacks on the computers and data systems of various government agencies. The attacks began as far back as December of 2012 and afterwards, "back doors" were left open so that the Anonymous computer hacker group could return to steal more information at will.

According to the FBI, Anonymous hackers accessed U.S. government computers as recently as a month ago. The information came via an FBI memo seen by Reuters who reports exclusively on the Anonymous computer hacker group breach.

The FBI memo, which went out to numerous government agencies last Thursday, detailed the FBI's findings concerning the Anonymous hackers security breach. Describing it as "a widespread problem that should be addressed," the FBI warned that the Anonymous hackers has managed to break onto data systems of the U.S. Army, the Department of Energy, Department of Health and Human Services, and more.

According to Reuters, Energy Secretary's chief of staff, Kevin Knobloch sent out an internal email with more details concerning the Anonymous hackers security breach. "Stolen data included personal information on at least 104,000 employees, contractors, family members and others associated with the Department of Energy, along with information on almost 2,0000 bank accounts."

According to the FBI, Anonymous hackers' breach of government computers is quite possibly linked to the Lauri Love case, where computers at the Department of Energy, Army, Department of Health and Human Services, the U.S. Sentencing Commission were all compromised. In that Love case, attacks are believed to have been caused by hackers taking advantage of a security flaw in Adobe's ColdFusion software. ColdFusion is often used to build websites. When contacted by Reuters however, Adobe spokeswoman Heather Edell believes if the attacks took place, they were likely due to agencies using software that had not been updated with the latest security patches.

While the breadth of the Anonymous hackers government security breach is yet unknown, investigators continue to quantify the effects of the attack. Meanwhile the FBI briefed government system administrators, instructing them on signs that might indicate the Anonymous computer hacker's group had compromised their systems.

A letter from early October mentions that the FBI is "very concerned" about the loss of banking information in the Anonymous hack. While the possibility of funds being stolen as a result of the data breach is real, it is worth noting that traditionally the Anonymous Hackers group are social activists, not common criminals. There was one notorious case — the Stratfor scandal — in which Anonymous hacker Jeremy Hammond took the fall for the group making roughly $700,000 in unauthorized charges on compromised credit cards and donating the money to charity. Since that time, however, no other cases of Anonymous hackers stealing money have occurred.

WATCH: Hacktivist Jeremy Hammond sentenced to 10 years in prison

What might be the motivation for Anonymous hackers to break into government computers and steal sensitive data this time? It seems one probable reason is revenge for the harsh prosecution of hackers, like Jeremy Hammond who was recently sentenced to 10 years in prison for his crime, or the penalties sought for Aaron Swartz, co-founder of Reddit who committed suicide in January of 2013.

What do you think of the warning the FBI issued concerning the Anonymous Hackers breach of government computers?