DHS has not yet developed national threat and vulnerability assessments or developed and exercised cybersecurity contingency plans, auditors said.
"Further, DHS continues to have difficulty in developing partnerships - as called for in federal policy - with other federal agencies, state and local governments, and the private sector," they noted.
According to GAO, several issues have made it hard for DHS to fulfill its cybersecurity responsibilities, including achieving organizational stability, gaining organizational authority, and overcoming hiring and contracting issues.
"Until it effectively confronts and resolves these underlying challenges, DHS will have difficulty achieving significant results in strengthening the cybersecurity of our nation's critical infrastructure," auditors said.
In response, Steven Pecinovsky, director of the departmental GAO liaison office at DHS, refuted the report's assertions.
"We agree that strengthening cybersecurity is central to protecting the nation's critical infrastructures and concur that much remains to be done," he wrote. "We do not, however, agree with the report's implication that the challenges experienced to date have prevented us from achieving significant restuls in improving the nation's cybersecurity posture."
Pecinovsky also disagreed with GAO's recommendations to identify and prioritize initiatives to deal with its challenges, or to establish performance metrics and milestones for the initiatives. The agency's cybersecurity plan already provides a priority list, measures and milestones, he said.
But Rep. Zoe Lofgren (D-Calif) said the report "only confirms what we have known all along- the DHS has failed to meet the responsibility for critical infrastructure protection."
"Even worse, this report proves that a national plan to secure our cyber networks is virtually nonexistent," she added. "There is no doubt that these vulnerabilities will continue to hamper our homeland security efforts if we do not make cybersecurity a major priority."
Lofgren said it is essential that DHS establish "organizational authority with an assistant secretary for cybersecurity" within the agency. She is the co-author of a bill that would create such a position. The current cybersecurity director in DHS is too many levels down in the hierarchy to be effective, she and others have argued.