Cybercriminals are distributing a new piece of malware that's based on the ZeuS computer Trojan through rogue emails that masquerade as US Airways online check-in notifications.
The spam campaign was launched on Mar. 20 and the malicious US Airways-themed emails contain a short description of the airline's online check-in procedure, said Kaspersky Lab security expert Dmitry Tarakanov, in a blog post on Tuesday.
They also include rogue links to view fake flight reservations on the US Airways website that actually point to domain names not connected to the company. Clicking on those links triggers a series of Web redirects that eventually lead to a BlackHole attack page.
BlackHole is a Web attack toolkit commonly used by cybercriminals to infect people's computers with malware. The toolkit exploits vulnerabilities in outdated versions of popular browser plug-ins like Java, Flash Player or Adobe Reader.
In this particular attack, BlackHole is being used distribute an information-stealing Trojan horse called GameOver, which is based on the much older ZeuS malware. The ZeuS source code was leaked on underground forums in May 2011, allowing cyber criminals to use it as a basis for the creation of new computer Trojans.
One particularly interesting aspect of the US Airways-themed attack is the high level of variation of its different elements. "Every object -- domains, links to javascripts, files with exploits, the downloader and ZeuS -- was frequently replaced with a new one," Tarakanov said.
The Kaspersky malware researcher believes that different spam templates might have been used by the attackers, in addition to the US Airways one, in order to target different categories of users.
"Cybercriminals are nothing if not original," Tarakanov said. "And even though this is not the first time they've used a flight-related trick, it's the first time this particular kind of spam has been detected."
As always, users are advised to inspect the destination of links included in email messages before clicking on them, even if the emails appear to originate from people they trust or companies they did business with.
Users should also keep the software installed on their computers up to date at all times, especially popular programs like Adobe Reader, Microsoft Office, Java, Flash Player or the different Web browsers.