Sniffing out RATS — remote access Trojans — is a challenge for even the most hardened cyber defender. Here’s a guide to help you in the hunt.
Earlier this month, the Office of Personnel Management reported that 21.5 million Americans had their social security numbers and other sensitive data stolen in the second breach to OPM’s background check database. In the wake of this massive breach, OPM Director Katherine Archuleta has resigned. It’s believed that the Sakula Remote Access Trojan (RAT) was associated with this attack.
RATs are very common and designed to provide the attacker with complete control over the victim’s system. They can be used to steal sensitive information, to spy on victims, and remotely control infected computers. RAT infections are typically carried out via spear phishing and social engineering attacks. Most are hidden inside heavily packed binaries that are dropped in the later stages of the malware’s payload execution.
Although RATs have been a mainstay in cyber attackers’ tool kits for some time, they continue to be very challenging to detect for the following reasons:
- They open legitimate network ports on the infected machines. Since this is a very common operation, it appears benign to most security products.
- They mimic legitimate commercial remote administration tools.
- They perform very surgical operations that do not resemble common malware techniques.
Here’s a rundown of seven of the most common RATs in use today:
RAT 1: Sakula is believed to be associated with the recent OPM attack. It is signed, looks like benign software, and provides the attacker with remote administration capabilities over the victim machine. Sakula initiates simple HTTP requests when communicating with its command and control (C&C) server. The RAT uses a tool called “mimkatz” to perform “pass the hash” authentication, which sends the hash to the remote server instead of the associated plaintext password.
RAT 2: KjW0rm is believed to be associated with the recent breach of TV stations in France. KjW0rm was written in VBS, which makes it even harder to detect. The Trojan creates a backdoor that allows the attacker to take control of the machine, extract information, and send it back to the C&C server. (For more information about KjW0rm read this SentinelOne blog.)
RAT 3: Havex targets industrial control systems (ICS). It is very sophisticated and provides the attacker with full control over the infected machine. Havex uses different variants (mutations) and is very stealthy. The communication with its C&C server is established over HTTP and HTTPS. Its footprint inside the victim machine is minimal.
RAT 4: Agent.BTZ/ComRat is one of the most notorious and well known RATs. Believed to be developed by the Russian government to target ICS networks in Europe, Agent.BTZ (also known as Uroburos) propagates via phishing attacks. It uses advanced encryption to protect itself from analysis, provides full administration capabilities over the infected machine, and sends extracted sensitive information back to its C&C server. Agent.BTZ uses advanced anti-analysis and forensic techniques.
RAT 5: Dark Comet provides comprehensive administration capabilities over the infected machine. It was first identified in 2011 and still infects thousands of computers without being detected. Dark Comet uses Crypters to hide it existence from antivirus tools. It performs several malicious administrative tasks such as: disabling Task Manager, Windows Firewall, and Windows UAC.
RAT 6: AlienSpy targets Apple OS X platforms. OS X only uses traditional protection such as antivirus. AlienSpy collects system information, activates webcams, establishes secure connections with the C&C server, and provides full control over the victim machine. The RAT also uses anti-analysis techniques such as detecting the presence of virtual machines.
RAT 7: Heseber BOT deploys Virtual Networking Computing (VNC) as part of its operation. Since VNC is a legitimate remote administration tool, this prevents Heseber from being detected by any antivirus software. Hesber uses VNC to transfer files and provide control over the infected machine.
Detecting RATs is very difficult due to the fact that they resemble commercial remote administration software. Meanwhile, traditional protection mechanisms that rely on static signatures are typically unable to detect new RAT variants. Monitoring system processes to detect the execution of malicious activity has proven to be an effective approach for sniffing out a rat.
This article was written originally by Ehud “Udi” Shamir, SentinelOne’s Chief Security Officer, for DARKReading magazine. Click here to read the original.
