A previously unknown threat actor has been observed exploiting critical security vulnerabilities in the MinIO high-performance object storage system to execute unauthorized code on compromised servers.
Security and incident response firm Security Joes disclosed this intrusion, noting that the attacker leveraged a publicly available exploit chain to introduce a backdoor into the MinIO instance.
These vulnerabilities, identified as CVE-2023-28432 and CVE-2023-28434, possess significant CVSS scores, and one of them was added to the U.S. Cybersecurity and Infrastructure Security Agency’s Known Exploited Vulnerabilities catalog in April 2023.
Security Joes’ investigation into the attack revealed that the threat actor utilized these vulnerabilities to obtain admin credentials and manipulate the MinIO client on the affected host. They accomplished this by triggering an update command specifying a MIRROR_URL, which effectively replaced the legitimate MinIO binary with a trojanized version.
This trojanized binary then acted as a backdoor, allowing the attacker to send and execute commands through HTTP requests, inheriting the system permissions of the initiating user. Notably, the tampered binary resembled “Evil MinIO,” an exploit posted on GitHub in April 2023, though there is currently no concrete evidence linking the two.
The malicious script introduced by the attacker is versatile and capable of targeting both Windows and Linux environments. It serves as a gateway to profile the compromised hosts, helping the attacker determine whether the execution should be terminated or continued based on the perceived value of the compromised system.
This dynamic approach highlights the threat actor’s strategic adaptability in optimizing their efforts according to the compromised system’s importance and potential impact.
