Security Experts:

Spring4Shell Vulnerability Exploited by Mirai Botnet

Cybersecurity firm Trend Micro on Friday confirmed some earlier reports that the new Spring4Shell vulnerability has been exploited by the Mirai botnet.

Two critical vulnerabilities have been patched recently in the popular Java application development framework Spring: CVE-2022-22965 (aka Spring4Shell and SpringShell) and CVE-2022-22963.

The flaws can be used for remote code execution and they both appear to have been exploited by malicious actors, with attacks reportedly starting before patches were made available by Spring developers.

While so far it appears that Spring4Shell is not as widely exploitable as Log4Shell — some industry professionals raised concerns about this possibility shortly after the disclosure of Spring4Shell — the vulnerability could still impact many organizations and several cybersecurity companies have reported seeing exploitation attempts.

Most of these exploitation attempts are designed to deliver a web shell that can allow the attacker to gain further access into the targeted organization’s environment.

However, it appears that a botnet powered by the notorious Mirai malware has also been exploiting Spring4Shell.

Chinese cybersecurity firm Qihoo 360 was the first to report Spring4Shell exploitation by Mirai, on April 1. Trend Micro on Friday confirmed those reports, explaining that CVE-2022-22965 has been leveraged to download the Mirai malware.

“We observed active exploitation of Spring4Shell wherein malicious actors were able to weaponize and execute the Mirai botnet malware on vulnerable servers, specifically in the Singapore region,” Trend Micro explained. “The Mirai sample is downloaded to the ‘/tmp’ folder and executed after permission change to make them executable using ‘chmod’.”

Mirai botnet operators are often quick to add newly disclosed vulnerabilities to their exploit arsenal. The botnet was also recently spotted exploiting the Log4Shell vulnerability.

Several cybersecurity companies have provided tools and other free resources that can be useful to defenders dealing with Spring4Shell.

Many vendors have been assessing the impact of Spring4Shell on their products. SecurityWeek provides links to the advisories and blog posts of major companies.

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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.