USB-based Threats Persist Despite Years of Software Updates
According to numbers coming from Internet security firm Bitdefender, Autorun-based threats, which typically spread via infected USB sticks, were responsible for 12 percent of global infections in the first quarter of 2012. Despite the fact that the Autorun feature was eliminated from operating systems in Windows Vista SP1 in 2008, worms that take advantage of the feature continue to infect systems worldwide.
“The magnitude of this threat — so many years after it should have disappeared — is astonishing,” said Catalin Cosoi, chief security researcher, Bitdefender. “Some of the heavy-hitters of the virus world, such as Downadup and Stuxnet, spread this way — prevention should be a simple matter.”
The mass introduction of USB storage devices and the apparition of the Autorun feature in Windows have been widely exploited since the early 2000s. Within five years, Autorun worms reached epidemic proportions autorun-based threats have dominated the malware landscape report since.
“You never know for certain where a USB stick may have been. It is worth making a habit of checking your portable drives,” said Adina Jipa, product marketing manager at Bitdefender USB.
In order to help address the threat, Bitdefender, has released a new version of its USB Immunizer, which helps protect against autorun-related threats.
1 – The Autorun.inf file is not malicious itself. It is used by some families of malware that copy themselves on USB sticks to force the computer to automatically execute them when an infected stick is plugged into a Windows-based PC.
2 – Among the most important families of malware that use the Autorun exploitation to spread are Stuxnet, Downadup, Sality, Rimecud or OnlineGames.
3 – Autorun-based malware can copy itself on MP3/MP4 players, mobile phones, SD cards (such as those in digital cameras) and other devices. When plugged in other PCs, the malware is executed automatically.
4 – Since autorun.inf files are plain-text files that can be opened and analyzed, malware creators obfuscate their creations to make them unreadable by humans. However, this is also their weak point. This degree of obfuscation is uncommon in text files and triggers AV detection.
5 – Trojan.AutorunInf (a detection that intercepts rogue autorun.inf files) has been the number one source of infection for more than three years in a row. During this time, it has helped various malware families infect millions of computers worldwide.
Bitdefender USB Immunizer is available here.