Cuba Ransomware Group Steals Credentials Via Veeam Exploit

CVE-2020-1472, widely known as "Zerologon," is an elevation-of-privilege flaw in how the Netlogon secure channel is established over the Netlogon Remote Protocol (MS-NRPC) on Microsoft domain controllers. An unauthenticated attacker with network reachability to a domain controller sends specially crafted Netlogon messages to establish a vulnerable secure channel and then runs a specially crafted application on the network to obtain domain administrator access. Successful exploitation yields domain administrator privileges, effectively full compromise of the Active Directory environment, and the flaw is known to be used in ransomware operations. Any organization running affected Windows Server versions (2008 through 20H2) as domain controllers is exposed, along with environments using Netlogon implementations from Samba and distributions or products from Fedora, openSUSE, Canonical (Ubuntu), Debian, Synology, and Oracle. Exploitation is highly active: a public Zerologon PoC/exploit is available, the flaw is on CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03, with known ransomware use), and EPSS estimates a 99.4% probability of exploitation within 30 days.

Do: Apply the vendor updates on all domain controllers and other affected systems immediately, following Microsoft's two-phase Netlogon secure channel guidance (the enforcement phase of the phased rollout began in Q1 2021). Audit Netlogon secure-channel connections and event logs for clients still using vulnerable connections before enabling full enforcement, and install updated packages for Samba and other Netlogon implementations from Fedora, openSUSE, Ubuntu, Debian, Synology, and Oracle. Given known ransomware use, prioritize patching any domain controller reachable from user networks, VPNs, or the internet.

Veeam Backup & Replication (VBR) contains a missing-authentication flaw (CWE-306) in its Cloud Connect component that lets an unauthenticated network attacker obtain encrypted credentials stored in VBR's configuration database. It is triggered simply by connecting to the exposed service, because the function that serves credential material performs no authentication check; no privileges or user interaction are required (CVSS 3.1: 7.5, network vector). With the recovered credentials, an attacker can gain access to backup infrastructure hosts, which has been used as an entry point and pivot for ransomware operations. Any organization running Veeam Backup & Replication is potentially affected, with the greatest risk where the VBR/Cloud Connect service is reachable from the internet. Exploitation is confirmed: CISA added the bug to its KEV catalog on 2023-08-22 with known ransomware use, the Cuba ransomware group has been observed stealing credentials through this exploit, and EPSS assigns a 77.6% near-term exploitation probability (100th percentile).

Do: Apply the fixes Veeam provides in its security advisory immediately — per CISA's KEV listing, patch per vendor instructions or discontinue use — prioritizing internet-facing Cloud Connect servers. After patching, rotate all credentials stored in the configuration database, since they should be considered exposed, and review those accounts for signs of misuse. Restrict network access to the VBR service from untrusted networks and check servers for exploitation indicators such as unexpected connections to the service or anomalous logins with stored credentials.