An article in the April issue of Virus Bulletin by two Symantec researchers says malware for the Apple Macintosh from January was used to create a botnet, and that the botnet attempted a denial-of-service attack.
The malware attacks at the time were noteworthy: They hid inside what apparently pirated copies of Apple's iWork software and Adobe Photoshop CS4. The programs were spread through BitTorrent and other peer-to-peer networks.
Symantec identified the malicious code as OSX.Iservice. According to Mario Ballano Barcena and Alfredo Pesoli of Symantec Ireland, OSX.Iservice created a backdoor on the systems that allowed control to be issued from a small number of specific hosts. A remote attacker could use a vocabulary of 31 commands: socks, system, httpget, httpgeted, rand, sleep, banadd, banclear, p2plock, p2punlock, nodes, leafs, unknowns, p2pport, p2pmode, p2ppeer, p2ppeerport, p2peertype, set, get, clear, abortall, p2pihistsize, p2pihist, platform, script, sendlogs, uptime, uid, shell, and rshell.
Barcena and Pesoli identify this as the first attempt to create a botnet of Macs, and say that in January the botnet attempted to perform a DoS attack on a Website. They find the Photoshop version of the bot especially interesting in that it abuses some of the Mac OS' own authorization interfaces.
The "iBotnet," as it has been dubbed, spread to only a few thousand Macs before it was identified, and is said to be easy to identify and remove if you are looking for it. The question, as I see it, is why you would look to identify it if you had been infected to begin with. The sort of person who installs a pirated program and runs an installer as root, which is required for this attack, isn't likely to be running an anti-malware program. Few enough innocent users on Macs run anti-malware software.
Kevin Haley, director of Symantec Security Response, noted that the pirated applications aren't actual working copies of the programs, and it's possible that some would notice that. It's not so clear that they would remove the application or that removing it would remove the bot. This is even clearer with the Photoshop version, according to Haley. It is quite possible that the user might never know the malware had been downloaded. However, the user might notice some problems on his or her machine. But even if thousands of Mac bots of this type are still out there, they're likely harmless at this point as they won't be connecting to a C&C.
What's important about this episode is that it does prove the concept of a Mac botnet. Like Linux and Vista, the Mac runs with users unprivileged by default and attempts either to fail or raise the prominence of potentially infectious activities such as installing privileged services.
But give a credulous or unsophisticated user a reason to install a privileged service, such as to install what they think is iWork, and they'll do it. There's your bot; nothing on the Mac makes it all that hard to do, and the really weak link is on the other side of the keyboard.
Security CenterEditor Larry Seltzer has worked in and written about the computer industry since 1983.
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