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Summary
A new critical zero-day vulnerability in the MOVEit Transfer software is being actively exploited by attackers to exfiltrate data from organizations. MOVEit Transfer is a managed file transfer (MFT) software, developed by Progress, designed to provide organizations a way to securely transfer files, which can be implemented on-premise or as a cloud SaaS platform. According to BleepingComputer, attackers have been actively exploiting MOVEit Transfer to download data from organizations.
Also, researchers have observed the presence of a webshell named human2.aspx in the root folder of multiple MOVEit servers, which indicates that an attacker could be running automated exploits against public facing MOVEit servers. At this point, there is no CVE assigned to this vulnerability yet.
Vulnerability
According to an advisory published by Progress on May 31, 2023, the zero-day consists of a SQL injection vulnerability in MOVEit’s web application that could lead to privilege escalation and remote code execution by un-authenticated attackers. A bad-intentioned person could take advantage of this vulnerability to access MOVEit Transfer’s database to steal data or alter database elements through SQL.
The vulnerability affects all versions of MOVEit Transfer. At this point, there are no further technical details about this vulnerability. As of June 2, 2023, the webshell that was found in vulnerable servers, and that was submitted to VirusTotal, remains undetected by antivirus engines.
When the webshell is accessed, it verifies the presence of a password specified in a header named “X-siLock-Comment”. If the password is wrong or the header wasn’t specified at all, the page returns a 404 status code, likely to prevent anyone else but the attacker from accessing the content.
If the webshell is correctly authenticated, the attacker is able to perform a series of actions based on the values of headers “X-siLock-Step1”, “X-siLock-Step2”, and “X-siLock-Step3”. The webshell provides the attacker with the ability to gather information and download files from the server, insert and delete a user account named “Health Check Service”, and steal configuration details of Azure Blob Storage accounts.