How Retro Malware Feeds the New Threat Wave

Last year saw a resurgence of the Zeus Trojan, a faded relic (we thought) from 2007. Whereas Zeus’s modus operandi used to be email spam, its more recent incarnation spreads via phishing emails, Facebook links and MMS messages containing the requisite links to infected websites.

McAfee Labs reported on the rise of “retro-malware” last year, noting that the Koobface worm -- nearly dormant by mid-2012 -- had hit a record number of victims on Facebook, Twitter, and other social networking sites in the first quarter of 2013, more than double the previous high-water mark in 2009.

In recent years, information security professionals have focused on preventing drive-by attacks launched by phishing attacks. However, these attacks have mutated into data-entry phishing attacks that don’t require any malware at all in their first phases. Instead, they employ the typical email with a link that takes recipients to Web pages that look legitimate and request a login. Credentials are collected as they are entered and no malware ever enters the system until the login and password are used in a later stage of the attack.

Palo Alto Networks recently released a report showing how old-school exploit techniques are being used in new ways and in new places. The report focused on common network applications such as FTP, RDP, SSL, NetBIOS, and UDP that are being leveraged as gateways or pivot points to communicate directly with endpoints. The company found that UDP has become the command-and-control channel for botnets as a safe place to “hide in plain sight,” with the ZeroAccess botnet showing up with greatest frequency. The ZeroAccess botnet is vintage, but the use of UDP as secret communications bandwidth is newly minted.

Late last, year, RDP “hacks” were in the news, with Brian Krebs reporting that Makost[dot]net rents access to more than 6,000 poorly configured Remote Desktop Protocol (RDP)-enabled servers following a brute-force attack that yielded a huge crop of weak credentials. This was no hack: The logins and passwords were valid, so the authentication system lets whoever purchased those credentials from the bad guys come right in.

Expanding security searchlight
In the case of RDP hacks, because the login and passwords used to gain access to these remote terminals are valid, no alerts were sent; technically there was no “hack.” But at the point of the exfiltration of sensitive data from endpoints, if these organizations had been watching for anomalous activity on those endpoints, an alarm could have been sounded. The same is true of the old ZeroAccess botnet colonizing the UDP layer. Anomalous endpoint behavior is the hallmark of infiltration, and something for which the information security searchlight must now regularly sweep.

Phishlabs’ research division is reporting this month that Vawtrak, a new version of the Gozi Prinimalka Trojan that first reared its ugly head in the mid-2000s, is widening its attack surface and expanding in complexity.

“Advanced Web injects” represent core functionality in this new configuration of the Trojan, which is taking advantage of the disruption of other major botnets such as Shylock and Spy Eye to gain new prominence in the cybercrime market. While financial institutions were the primary target of Vawtrak in the early days, new targets include online retailers, game portals, social networks, and analytics firms in the United States, United Kingdom, Turkey, Slovakia, and Australia.

We all know that cyber criminals and nation states are frighteningly well organized and actively collaborating to take down shared targets in mutually beneficial ways. The best way to add defense-in-breadth to our defense-in-depth techniques is to actively share threat intelligence among ourselves, as professionals, and between our time-tested and next-generation security products.

If we can record “normal” activity over time, regularly monitor that activity, and devote analyst time to proactively study anomalous behavior in all the new places they’re attempting to hide, we have a better shot at catching threats in all their evolutionary stages.