When RATs Become a Social Engineer’s Best Friend

Jane, the senior fraud analyst in a top-tier bank, was looking at the latest series of reported online banking fraud cases and shook her head. This can’t be right, she decided. The fraudulent money transfer was coming from the victim’s device, which normally indicates some sort of Trojan-induced Man-in-the-Browser (MITB) attack designed to defeat device recognition and geo-location analysis. But these MITB attacks are normally picked up by the state-of-the-art malware detection service used by the bank.

She looked at the list of alerts and double-checked. There was nothing there. Was it some sort of new Trojan that went undetected by the system? If so, the Trojan operators must have known they have safe passage; they spent a long time in the account, and the money transfer they made was enormous. It’s as if they knew it wouldn’t be detected by any of the existing lines of defense. 

They were right about that, Jane thought, and picked up the phone to call the Internet user who reported the fraud. The story she heard made her realize she was facing something totally new… 

Remote Administration Tools, or RATs, started as completely harmless remote support tools, the kind that a help desk would use to support users whose PC needed attention. In fact, every major operating system, including mobile ones, have remote access protocols embedded in the OS level. But while RATs are a relatively new entrant in the growing arsenal of tools available to online banking fraudsters, state-sponsored hackers have been using them for a long time. Since 2009, wave after wave of Advanced Persistent Threats (APT) campaigns used spear phishing to install RATs on employee machines in thousands of corporations worldwide. These attacks create invisible tunnels that allow an outsider to completely control a victim’s device from anywhere. 

RAT capabilities based on VNC back-connect later appeared as a new feature in advanced banking Trojans such as Citadel, as well as a hoard of next-generation Zeus clones. The fraudsters learned from government hackers that RATs are an extremely powerful weapon, allowing attackers to not only harvest information or run automated scripts in browsers, but to actually gain full remote control of a device, and access a victim’s bank account from their own machine. 

Today, RATs are a popular tool commonly used by cybercriminals. Dyre is currently the most widespread Trojan that uses RAT; Dridex, whose operation was recently disrupted by law enforcement, was also heavily using a RAT capability. Other Trojans include Neverquest, Shifu and many Zeus clones that feature VNC functionality with back-connect. Recently, there has been a spinoff of these RAT attacks: Social RATs.

In this rapidly growing social engineering attack, the victim gets a phone call from someone claiming to be from their bank, internet provider, or other trusted third party. The fraudster then gets the victim to download a commercially available remote administration tool, such as TeamViewer, in order to help fix the “problem”. 

Providing a rogue help desk with remote access rights into your PC is not something most readers of this article would do, but good social engineering is, at times, extremely convincing and effective. The banking industry is particularly vulnerable due to its lack of effective fraud detection for remote access attacks.

After the RAT is installed?

While on the phone, attackers instruct victims to go through “security checks” to verify the safety of their accounts by logging into their bank accounts. Even after victims believe themselves to be logged out, an attacker can linger undetected. Part of the reason banks are experiencing a growing number of socially engineered attacks is because they are cheap to execute and offer a huge payoff to attackers; with limited technological training, attackers can send a quick email, or briefly chat over the phone, and access someone’s entire life savings.

A similar problem exists in corporate banking. From a regulatory perspective, there are no requirements for a bank to make a business customer whole if it lost money due to fraud. However, publicity surrounding large fraud cases has made many banks realize that while they do not have the obligation to do so, making customers confident in their online banking usage is in their best interest.

Social RAT attacks stretch this dilemma even further: first, they involve higher-than-usual monetary losses, and second, falling victim to a ploy in which you end up granting someone remote control over your device is viewed by many banks as crossing the line from naiveté to gross negligence. This spells trouble for business banking, as it could set a dangerous precedent where trust between banks and their customers erode quickly.

Two factors contribute to the success of rogue help desk RAT campaigns. First, users are familiar with the concept of help desks that ask permission to take over their device. So, given the right social engineering, they’ll be susceptible to manipulation. The second issue: existing security controls do not detect RATs. 

To help close the gaps, banks can protect themselves by educating customers about social engineering threats. Users should be encouraged to refuse unsolicited help and contact their banks or other financial institutions if they receive suspicious emails, text messages or phone calls.  Moreover, customers should be made aware of ways they can verify conversations with customer service representatives.