On June 5, 2024, SolarWinds disclosed CVE-2024-28995, a high-severity directory traversal vulnerability affecting their Serv-U file transfer server, which comes in two editions (Serv-U FTP and Serv-U MFT). Successful exploitation of the vulnerability allows unauthenticated attackers to read sensitive files on the target server. Rapid7’s vulnerability research team has reproduced the vulnerability and confirmed that it’s trivially exploitable and allows an external unauthenticated attacker to read any file on disk, including binary files, so long as they know the path and the file is not locked (i.e., opened exclusively by something else).

CVE-2024-28995 is not known to be exploited in the wild as of 9 AM ET on June 11. We expect this to change; Rapid7 recommends installing the vendor-provided hotfix (Serv-U 15.4.2 HF 2) immediately, without waiting for a regular patch cycle to occur.

High-severity information disclosure issues like CVE-2024-28995 can be used in smash-and-grab attacks where adversaries gain access to and attempt to quickly exfiltrate data from file transfer solutions with the goal of extorting victims. File transfer products have been targeted by a wide range of adversaries the past several years, including ransomware groups.

Internet exposure estimates for SolarWinds Serv-U vary substantially based on the query used — e.g., 9,470 Serv-U instances by one count vs. 5,434 using a different query. (Note that exposed does not automatically mean vulnerable, however.)

Mitigation guidance

SolarWinds Serv-U 15.4.2 HF 1 and previous versions are vulnerable to CVE-2024-28995, per the vendor advisory. The vulnerability is fixed in SolarWinds Serv-U 15.4.2 HF 2. SolarWinds Serv-U customers should apply the vendor-provided hotfix immediately.

Rapid7 customers

InsightVM and Nexpose customers can assess their exposure to CVE-2024-28995 with an unauthenticated vulnerability check available as of the Monday, June 10 content release.

InsightIDR and Managed Detection and Response customers have existing detection coverage through Rapid7's expansive library of detection rules. Rapid7 recommends installing the Insight Agent on all applicable hosts to ensure visibility into suspicious processes and proper detection coverage. Below is a non-exhaustive list of detections that are deployed and may alert on post-exploitation behavior related to this vulnerability:

• Suspicious Web Server Request - Successful Path Traversal Attack