Rapid 7 - Critical Vulnerabilities in WS_FTP Server

On September 27, 2023, Progress Software published a security advisory on multiple vulnerabilities affecting the Ad Hoc Transfer module in WS_FTP Server, a secure file transfer solution. There are a number of vulnerabilities in the advisory, two of which are critical (CVE-2023-40044 and CVE-2023-42657).

Rapid7 is not aware of any exploitation in the wild as of September 29, 2023. Our research team has identified what appears to be the .NET deserialization vulnerability (CVE-2023-40044) and confirmed that it is exploitable with a single HTTPS POST request and a pre-existing ysoserial.net gadget.

The vulnerabilities in the advisory span a range of affected versions, and several affect only WS_FTP servers that have the Ad Hoc Transfer module enabled. Nevertheless, Progress Software’s advisory urges all customers to update to WS_FTP Server 8.8.2, which is the latest version of the software. Rapid7 echoes this recommendation.The vendor advisory has guidance on upgrading, along with info on disabling or removing the Ad Hoc Transfer module.

The critical vulnerabilities are below — notably, NVD scores CVE-2023-40044 as only being of “high” severity, not critical:

• CVE-2023-40044: In WS_FTP Server versions prior to 8.7.4 and 8.8.2, the Ad Hoc Transfer module is vulnerable to a .NET deserialization vulnerability that allows an unauthenticated attacker to execute remote commands on the underlying WS_FTP Server operating system. The vulnerability affects all versions of the WS_FTP Server Ad Hoc module. Progress Software’s advisory indicates that WS_FTP Server installations without the Ad Hoc Transfer module installed are not vulnerable to CVE-2023-40044.
  
• CVE-2023-42657: WS_FTP Server versions prior to 8.7.4 and 8.8.2 are vulnerable to a directory traversal vulnerability that allows an attacker to perform file operations (delete, rename, rmdir, mkdir) on files and folders outside of their authorized WS_FTP folder path.  Attackers could also escape the context of the WS_FTP Server file structure and perform the same level of operations (delete, rename, rmdir, mkdir) on file and folder locations on the underlying operating system.

Additional (non-critical) vulnerabilities are listed below. See Progress Software’s advisory for full details:

• CVE-2023-40045: In WS_FTP Server versions prior to 8.7.4 and 8.8.2, the Ad Hoc Transfer module is vulnerable to reflected cross-site scripting (XSS). Delivery of a specialized payload could allow an attacker to execute malicious JavaScript within the context of the victim's browser.
• CVE-2023-40046: The WS_FTP Server manager interface in versions prior to 8.7.4 and 8.8.2 is vulnerable to  SQL injection, which could allow an attacker to infer information about the structure and contents of the database and execute SQL statements that alter or delete database elements.
• CVE-2023-40047: The WS_FTP Server Management module in versions prior to 8.8.2 is vulnerable to stored cross-site scripting (XSS), which could allow an attacker with administrative privileges to import an SSL certificate with malicious attributes containing cross-site scripting payloads.  Once the cross-site scripting payload is successfully stored, an attacker could leverage this vulnerability to target WS_FTP Server admins with a specialized payload which results in the execution of malicious JavaScript within the context of the victim's browser.  
• CVE-2023-40048: The Manager interface in WS_FTP Server version prior to 8.8.2 was missing cross-site request forgery (CSRF) protection on a POST transaction corresponding to a WS_FTP Server administrative function.
• CVE-2023-40049: In WS_FTP Server version prior to 8.8.2, an unauthenticated user could enumerate files under the 'WebServiceHost' directory listing.  
• CVE-2022-27665: WS_FTP Server 8.6.0 is vulnerable to reflected XSS (via AngularJS sandbox escape expressions), which allows an attacker to execute client-side commands by inputting malicious payloads in the subdirectory search bar or Add folder filename boxes. For example, there is Client-Side Template Injection via subFolderPath to the ThinClient/WtmApiService.asmx/GetFileSubTree URI.

Mitigation guidance

Progress Software security advisories have borne increased scrutiny and garnered broader attention from media, users, and the security community since the Cl0p ransomware group’s May 2023 attack on MOVEit Transfer. Secure file transfer technologies more generally continue to be popular targets for researchers and attackers.

While these vulnerabilities are not known to be exploited by adversaries at this time, we would advise updating to a fixed version as soon as possible, without waiting for a typical patch cycle to occur. As noted in the advisory, "upgrading to a patched release using the full installer is the only way to remediate this issue. There will be an outage to the system while the upgrade is running."

The optimal course of action is to update to 8.8.2 as the vendor has advised. If you are using the Ad Hoc Transfer module in WS_FTP Server and are not able to update to a fixed version, consider disabling or removing the module.

See Progress Software's advisory for the latest information.

Rapid7 customers

InsightVM and Nexpose customers running WS_FTP will be able to assess their exposure to all eight of the CVEs in this blog with authenticated vulnerability checks expected to be available in today’s (September 29) content release.

from Rapid7 Cybersecurity Blog https://blog.rapid7.com/2023/09/29/etr-critical-vulnerabilities-in-ws_ftp-server/