A criminal gang is using software tools normally reserved for computer network administrators to infect thousands of PCs in corporate and government networks with programs that steal passwords and other information, a security researcher has found. The new form of attack indicates that little progress has been made in defusing the threat of botnets, networks of infected computers that criminals use to send spam, steal passwords and do other forms of damage, according to computer security investigators. Several security experts say that although attacks against network administrators are not new, the systematic use of administrative software to spread malicious software...