A second piece of Trojan-like malware is currently threatening Macs, say security vendors. OSX.Lamzev.A, also known as OSX.TrojanKit.Malez, allows hackers to install a backdoor on a victim's computer and thereby assume control of it. The software is said not to be a true Trojan, however, as an attacker must already have access to the target Mac to make use of the code.