WASHINGTON — The White House plans to issue an executive order on Friday to replace a flawed patchwork of computer security safeguards exposed by the disclosure of hundreds of thousands of classified government documents to WikiLeaks last year.

The order by President Obama culminates a seven-month governmentwide review of policies and procedures involving the handling of classified information, and recommendations on how to reduce the risk of breaches.

The directive enshrines many stopgap fixes that the Pentagon, the State Department and the Central Intelligence Agency made immediately after the initial WikiLeaks disclosures last November. Since then, for instance, the military has disabled 87 percent of its computers to prevent people from downloading classified data onto memory sticks, CDs or DVDs.

The Pentagon has also developed procedures to monitor and detect suspicious behavior on classified computer systems. And the State Department stopped distributing its diplomatic cables over a classified e-mail system used by many in the military, including Pfc. Bradley E. Manning, who is accused of leaking the classified documents to WikiLeaks.