In the latest sign that the problem persists, researchers at the federally funded MITRE lab said this week that many customers of Intel Corp still had not adopted revised security designs Intel distributed in March after the MITRE team found new vulnerabilities in the start-up process. Intel’s point person on the issue, Bruce Monroe, said he did not know how many suppliers and computer makers had followed Intel’s recommendations. “We asked them to let us know.” The stubborn glitches illustrates how such well-funded spying programs as those exposed by former National Security Agency contractor Edward Snowden can continue to succeed against targets that depend on a complex supply chain.