A remote code execution bug in the Chinese open source framework ThinkPHP is being actively used by threat actors to implant a variety of malware, primarily targeting Internet of Things (IoT) devices.
Background
Over the last few months, attackers have been leveraging CVE-2018-20062, a remote code execution (RCE) vulnerability in Chinese open source PHP framework ThinkPHP, to implant a variety of malware. While the vulnerability was patched on December 9, 2018, a proof of concept (PoC) was published to ExploitDB on December 11.
Analysis
Shortly after the publication of the PoC, researchers observed an uptick in attackers scanning for vulnerable versions of ThinkPHP. On December 20, Trend Micro published a blog about a new IoT botnet called Miori that spreads using CVE-2018-20062. According to Trend Micro researchers, additional IoT malware known as IZ1H9 and APEP began to utilize the same vulnerability as an infection vector.
In January 2019, the Akamai security team not only observed this vulnerability being used in attacks to implant IoT malware, but also discovered it being used to spread cryptocurrency miners and Windows malware. Trend Micro posted another blog on January 25, detailing the usage of this vulnerability by IoT malware known as Hakai and Yowai.
On February 4, researchers at Check Point named ThinkPHP as the initial infection vector in attacks targeting systems to implant a backdoor trojan known as SpeakUp.
Despite being patched in December 2018, CVE-2018-20062 has become a popular vulnerability for attackers looking to implant IoT malware onto systems. The vulnerability has also been observed in the propagation of other types of malware like cryptocurrency miners and trojans. We expect this to remain a popular exploit with attackers as long as systems remain unpatched.
Solution
This vulnerability was patched in ThinkPHP versions 5.0.23 and 5.1.31. Users are strongly encouraged to upgrade to a newer version of the framework.
Identifying affected systems
A list of Nessus plugins to identify these vulnerabilities can be found here.
Get more information
- National Vulnerability Database: CVE-2018-20062
- PoC: ThinkPHP 5.x < v5.0.23,v5.1.31 Remote Code Execution
- With Mirai Comes Miori: IoT Botnet Delivered via ThinkPHP Remote Code Execution Exploit
- ThinkPHP Exploit Actively Exploited In The Wild
- ThinkPHP Vulnerability Abused by Botnets Hakai and Yowai
- SpeakUp: A New Undetected Backdoor Linux Trojan
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