A state audit of the Prince George’s County school system found that weak financial controls and insufficient oversight have resulted in $1 million in overpayments to employees and have left the district’s computer network vulnerable to attack.

The audit, which the Office of Legislative Audits released Wednesday, found serious problems in the district’s human relations and Internet security departments and questioned $1 million in six sole-source contracts for which the school system apparently had no documentation.

Auditors reviewed the county school system’s financial records from January 2011 to June 2012. Thomas J. Barnickel III, the legislative auditor, said he was troubled that many of the issues the recent audit identified were problems the state found six years ago during the previous state audit of Maryland’s second-largest school district.

“Serious actions need to be taken to address these long-standing issues,” Barnickel said.

The school system operates a $1.7 billion budget, and Prince George’s officials said the auditors’ concerns are mistakes that date to previous school administrations. Barnickel said some of the management problems are linked to the lack of long-term stability. The district has had seven superintendents in 14 years.

Prince George’s has been working to improve its academics and its administration, in part to address such problems. Last year, County Executive Rushern L. Baker III (D) sought a takeover of the school system and received greater authority over the district in a wide-ranging move to improve the schools and, in turn, the county.

Baker hired Schools Chief Executive Kevin M. Maxwell after the leadership overhaul, hoping the longtime educator would come in from Anne Arundel County and turn the schools in a new direction. Max Pugh, a spokesman for the school system, said Maxwell plans to use the audit report as a guide for improving the system.

“Although this report was based on data and management prac­tices implemented under the former administration, we consider this audit a good road map to improving our financial and management practices,” he said.

Auditors found problems in several areas, including the overpayments to employees.

The report said that school system officials paid some contract employees for days they did not work, processed duplicate payments to some employees, paid some employees who were on unpaid leave, improperly calculated leave payouts to terminated employees and inaccurately recorded employee separation dates. As of October 2012, the overpayments totaled $1 million. The district is trying to recover $780,000 through an outside collection agency.

The auditors also discovered that the connections from the school system’s student computer labs “were not properly restricted from accessing critical . . . internal network resources.”

The report says the problem with the information system and contracting were reported in the state’s previous audit. Of the state’s 23 findings, 12 were identified in the report six years ago.

“That’s pretty sad because these problems could have been fixed years ago,” said Dave Cahn, who advocates for accountability and transparency in the county’s school system. “The audit findings were ignored. Why have an audit if nothing is going to be done about it? . . . All that time, our system could have been running more efficiently, legally and more in compliance with the rules. This is money that could have gone to education.”

The chairman of the county school board, Segun C. Eubanks, said the board, Baker and Maxwell will work to ensure that management practices improve.

“I think the administration is committed to addressing some of the financial issues,” Eubanks said. “In a system our size, making mistakes is inevitable, but repeating mistakes is a problem.”

The audit also found that the school system failed to use its automated bus-routing software to ensure that school buses were being used in a cost-effective manner. According to the audit, the average utilization of the school system’s 1,150 buses was less than 50 percent in 2011, when the district spent $96 million on transportation and perhaps could have spent far less.

The district also could not produce documentation to explain why a schools energy-performance contract had no completion date or how the contractors could explain that they met the guaranteed savings of $184.5 million.

“This shows there are opportunities to tighten up controls,” said state Sen. James C. Rosapepe (D-Prince George’s), co-chairman of the state Joint Audit Committee. “Making sure the money is managed well is important to the kids as well as the taxpayers.”