(credit: Jeremy Brooks) gA stealthy backdoor undetected by antimalware providers is giving unknown attackers complete control over at least 100 Linux servers that appear to be used in business production environments, warn researchers. In a blog post published Wednesday, Montreal-based GeoSecure claimed that a piece of malware dubbed "Chaos" is infecting poorly secured systems by guessing weak passwords protecting secure shell application administrators use to remotely control Unix-based computers.