Ravaging RDP Servers? Backdoor Trojan Ramps Up Enterprise Risk

Trojan-laden malware remains a huge problem for enterprises and individual users alike. As noted by Palo Alto Networks, some cybercriminals are targeting users with creative Mac OS X malware that uses a PDF detailing Russian space program projects over the next decade as a decoy to infect systems with information-stealing code.

Softpedia, meanwhile, reported that enterprises have more to fear from a new set of brute-force remote desktop protocol (RDP) attacks that use a backdoor Trojan to infect connected servers and grab everything from banking credentials to tax data and browser cookies. Here’s a look at the new RDP risk.

Dangerous Desktops

Microsoft developed RDP to enable out-of-office workers to connect with desktop PCs. This capability is essential in corporate environments where users are accustomed to full mobile privileges and remote, 24/7 access. Users only need an RDP client on their remote device, while corporate networks require RDP servers.

The problem? RDP ports are often left open, connected to the internet at large, and they leverage common username and password combinations. Softpedia noted that a new Trojan variant known as Trojan.sysscan is now scanning the web for open ports and brute-forcing these connections to gain access.

Once installed, the malware creates a hidden admin account that grants boot persistence and sets all RDP ports to permanently open, allowing for future connections or compromises. Corporate data is then collected from hosted desktops and sent using an unencrypted HTTP request to remote servers. If this fails, most attackers are brazen enough to log in and manually copy the stolen data.

Backdoor Trojan Trots Across the Globe

Security firm Guardicore, which discovered the new threat, reported that attackers commonly use IPs in the United Arab Emirates to store data and an IP in Germany to scan for any open RDP ports.

This isn’t the only RDP threat making the rounds. According to PC World, Kaspersky Lab recently discovered a brute-force RDP campaign in Brazil, called Trojan-Ransom.Win32.Xpan, which went after open RDP ports on hospital networks. Once infected, any antivirus products on the server were disabled and the Xpan ransomware was installed, encrypting all critical files and demanding a payout.

This avenue of attack is popular in Brazil, which has more compromised server details available online than any other country. Fortunately for users, Kaspersky found a way to recover the files thanks to an error in the Trojan’s original code.

Stemming the Tide

While RDP attacks are nothing new, they persist because they represent an avenue of easy opportunity for cybercriminals. Stemming the tide starts with reasonable RDP use. Whenever possible, companies need to get remote servers off the public internet and away from backdoor Trojan risk.

If leveraging an open RDP is the only way to ensure remote connection access, however, password and login rules that govern other high-value tech assets must apply. Stock credentials must be immediately changed, usernames and passwords must be unique, and these credentials should be regularly changed.

In addition, companies should invest in cloud-based monitoring tools separate from potentially compromised systems. These tools can provide warning of potential infection and help remediate RDP servers after an attack.

The bottom line is that remote desktop access increases business risk. Add in stealthy, persistent Trojans, and a brute-force attack could lead to ravaged RDP along with compromised corporate credentials.

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Douglas Bonderud

Freelance Writer

A freelance writer for three years, Doug Bonderud is a Western Canadian with expertise in the fields of technology and...