In one instance, hacker tools for stealing passwords and other files were found on two internal Homeland Security computer systems. The agency's headquarters sought forensic help from the department's own Security Operations Center and the U.S. Computer Emergency Readiness Team it operates with Carnegie Mellon University.
In other cases, computer workstations in the Coast Guard and the Transportation Security Administration were infected with malicious software detected trying to communicate with outsiders; laptops were discovered missing; and agency Web sites suffered break-ins.
The chairman of the House Homeland Security Committee, Rep. Bennie Thompson, D-Miss., said such problems undermine the government's efforts to encourage companies and private organizations to improve cyber security.
"What the department is doing on its own networks speaks so loudly that the message is not getting across," Thompson said.
Congressional investigators, expected to testify Wednesday during an oversight hearing about the department's security lapses, determined that persistent weaknesses "threaten the confidentiality, integrity and availability of key DHS information and information systems," according to a new report from the Government Accountability Office being released later in June.
The Homeland Security Department's chief information officer, Scott Charbo, assured lawmakers his organization was working to prevent such problems.
"We need to increase our vigilance to ensure that such incidents do not happen again," Charbo wrote in testimony prepared for Wednesday's hearing. "The department takes these incidents very seriously and will work diligently to ensure they do not recur."
The computer problems disclosed to the House Homeland Security subcommittee occurred during fiscal 2005 and fiscal 2006, and occurred at DHS headquarters and many of the department's agencies, including TSA, the Coast Guard, Federal Emergency Management Agency, Customs and Border Protection and others.
The subcommittee's chairman, Rep. Jim Langevin, D-R.I., said break-ins to government computer networks and theft of information are "one of the most critical issues confronting our nation, and we must deal with this threat immediately."
All the problems involved the department's unclassified computer networks, although DHS officials also have acknowledged to lawmakers dozens of incidents they described as "classified spillage," in which secret information was improperly transmitted or discussed over non-secure e-mail systems