Security Experts:

Connect with us

Hi, what are you looking for?

SecurityWeekSecurityWeek

Malware & Threats

Worm Uses ShellShock to Infect QNAP Network Storage Systems

Researchers have uncovered a worm that’s designed to plant backdoors on QNAP network-attached storage (NAS) devices. The malware is distributed through the exploitation of the GNU Bash vulnerability known as ShellShock.

Researchers have uncovered a worm that’s designed to plant backdoors on QNAP network-attached storage (NAS) devices. The malware is distributed through the exploitation of the GNU Bash vulnerability known as ShellShock.

Cybercriminals started exploiting ShellShock to gain full access to the contents of NAS devices developed by Taiwan-based QNAP shortly after the existence of the vulnerability came to light. The vendor released updates to address the flaw in its product at the beginning of October, but because the patches are not easy to apply many systems remain vulnerable.

The SANS Institute reports that a worm is currently spreading among QNAP devices, which run an embedded Linux operating system, by exploiting the Bash vulnerability.

“The attack targets a QNAP CGI script, ‘/cgi-bin/authLogin.cgi’, a well known vector for Shellshock on QNAP devices,” Johannes Ullrich of the SANS Internet Storm Center wrote in a blog post. “This script is called during login, and reachable without authentication. The exploit is then used to launch a simple shell script that will download and execute a number of additional pieces of malware.”

One of the worm’s malicious components is designed for click fraud and it targets the online advertisement network JuiceADV.

The threat also sets up backdoors on infected devices by creating an SSH server on port 26, by adding a user (named “request“) with administrator privileges, and by copying some CGI scripts with backdoor functionality to the “cgi-bin” directory. The malware modifies the “autorun.sh” file in order to run the backdoors on reboot.

Researchers have also noticed that the worm sets the DNS server on the infected machine to 8.8.8.8, which is actually Google’s DNS server. It’s possible that the attackers do this in order to get a more reliable DNS server, since as Ullrich explains, QNAP devices sometime use internal DNS servers which aren’t fully recursive. By using this method, the attackers might also be trying to evade potential logging mechanisms.

The worm is dangerous because it abuses infected systems to look for other vulnerable devices on the network, Ullrich noted.

Interestingly, the malware also patches the ShellShock vulnerability on infected devices by downloading the applying the security updates from QNAP. Experts believe the threat does this to prevent additional exploitation.

NAS devices are also a tempting target for ransomware attacks. This summer, a piece of ransomware dubbed SynoLocker was used to infect Synology NAS servers by exploiting a vulnerability that was patched in December 2013.

Written By

Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.

Click to comment

Expert Insights

Related Content

Malware & Threats

Microsoft plans to improve the protection of Office users by blocking XLL add-ins from the internet.

Cybercrime

CISA, NSA, and MS-ISAC issued an alert on the malicious use of RMM software to steal money from bank accounts.

Cybercrime

Chinese threat actor DragonSpark has been using the SparkRAT open source backdoor in attacks targeting East Asian organizations.

Application Security

Electric car maker Tesla is using the annual Pwn2Own hacker contest to incentivize security researchers to showcase complex exploit chains that can lead to...

Malware & Threats

Cybercrime in 2017 was a tumultuous year "full of twists and turns", with new (but old) infection methods, a major return to social engineering,...

Cybercrime

A recently disclosed vBulletin vulnerability, which had a zero-day status for roughly two days last week, was exploited in a hacker attack targeting the...

Malware & Threats

Norway‎-based DNV said a ransomware attack on its ship management software impacted 1,000 vessels.

Malware & Threats

A GitHub Codespaces feature meant to help with code development and collaboration can be abused for malware delivery.