Lynx ransomware case reveals nine day RDP driven intrusion chain

Lynx ransomware operators executed a nine day intrusion culminating in backup destruction and multi server encryption, using valid credentials and Remote Desktop Protocol in a sequence closely aligned with ATT&CK techniques T1133 (External Remote Services), T1078 (Valid Accounts), T1135 (Network Share Discovery), T1560.001 (Archive via Utility) and T1486 (Data Encrypted for Impact). According to the DFIR case study, the attack began on an internet exposed RDP server where the threat actor logged in with already compromised credentials, likely purchased from an initial access broker or obtained via an infostealer or breach reuse. Within minutes they pivoted to a domain controller using a separate compromised domain admin account, created look alike privileged users and installed AnyDesk for persistence, although they continued to favor RDP for hands on activity. Over subsequent days, the actor performed extensive reconnaissance using Windows utilities and tools like SoftPerfect Network Scanner, mapping domain controllers, hypervisors, file servers and backup infrastructure. They browsed multiple network shares and later compressed sensitive data from two file servers using 7 Zip, exfiltrating archives via the temp dot sh file sharing service, aligning with T1567 (Exfiltration over Web Service). The final phase saw the actor connect to backup servers and file servers, delete backup jobs from Veeam Backup and Replication and deploy the Lynx encryptor, dropping a payload named w dot exe and executing it with parameters tuned for fast partial encryption across targeted drives. For enterprises, this case underscores how quietly an adversary can operate with valid credentials and no obvious brute force or malware beacons, especially when RDP is the main remote control channel. By the time encryption began, the attackers had already harvested and exfiltrated data, disabled recovery paths and established multiple privileged accounts, leaving the victim with limited options beyond negotiation or painful rebuild. Time to ransomware of roughly 178 hours illustrates how intruders can move deliberately but still stay ahead of traditional detection and response cycles in understaffed environments. Mitigation efforts should start with aggressive reduction of exposed RDP services, enforcement of MFA and robust monitoring of RDP session behavior, including anomalous admin logons and lateral movement patterns. Detection teams should tune telemetry for tools like SoftPerfect NetScan and 7 Zip used in bulk archiving, and watch for connections to temporary file sharing services such as temp dot sh that may signal exfiltration staging. Organizations must also harden backup platforms, restrict who can modify or delete jobs and logs, and maintain offline or immutable backup copies that cannot be removed via the same credentials used to manage production systems.