SAN FRANCISCO — The same tools that help millions of Americans work from home are being exploited by cybercriminals to break into the computer networks of retailers like Target and Neiman Marcus.

The Homeland Security Department, in a new report, warns that hackers are scanning corporate systems for remote access software — made by companies like Apple, Google and Microsoft — that allows outside contractors and employees to tap into computer networks over an Internet connection.

When the hackers discover such software, they deploy high-speed programs that guess login credentials until they hit the right one, offering a hard-to-detect entry point into computer systems.

The report, which Homeland Security produced with the Secret Service, the National Cybersecurity and Communications Integration Center, Trustwave SpiderLabs, an online security firm based in Chicago, and other industry partners, is expected to be released on Thursday. It provides insight into what retailers are up against as hackers find ways into computer networks without tripping security systems.