Edge Device Exploitation: VPN Zero-Day

Your shift opens with a perimeter security alert: an exploit attempt was flagged against the internet-facing gateway corp-ivnt-gw-01 from an external IP. Before tracing the attacker, establish provenance; pivot to the SIEM panel, locate the exploit-detection event, and determine which internal monitoring system raised it (the value recorded in its log source field).

With the detecting sensor confirmed, pivot to what the exploit actually achieved. During the gateway compromise the exposed web service was driven to spawn a process it should never launch, a clear sign the adversary obtained command execution. Work the XDR process hierarchy for corp-ivnt-gw-01 and identify the name of that anomalous child process.

Having confirmed the interpreter the exploit spawned, follow what it did next. That process reached out to external infrastructure and wrote a file to the gateway's disk: the attacker's first-stage implant. Using the XDR file artifacts and the suspicious process command line on corp-ivnt-gw-01, identify the exact filename written to disk.

The implant on the gateway did not act alone; shortly after it landed, an outbound HTTP request left the environment toward attacker-controlled infrastructure. A SIEM network-proxy event was flagged high severity against the usual informational noise. Inspect that flagged proxy event and determine the external domain the internal host tried to reach.

You now know where the gateway implant tried to phone home. The good news: the perimeter held. When the gateway shell attempted a follow-up connection back to that same external host, an automated firewall policy denied the session. Inspect the firewall panel, locate the blocked outbound session, and name the defensive policy that stopped it.

Containment bought time, but an adversary who exploited the gateway will try to survive a reboot. An alert fired for potential persistence on corp-ivnt-gw-01: the init system was seen spawning a long-running service process that should not be a direct child of init. Examine the XDR process hierarchy for the gateway and submit the full command line used to launch that persistent service.

With the gateway foothold mapped, widen the scope inward. During host triage of the directory server srv-ldap-01, a root cron entry was found running a local shell script shortly after the edge-device compromise, a likely lateral-movement or staging step deeper in the network. Review the relevant SIEM cron message and identify the name of the script that was executed.

The investigation's final thread leads off the perimeter and onto an internal endpoint. Several days after the gateway was compromised, follow-on activity surfaced on the developer workstation wks-devops-01: an operator launched a PowerShell script tied to edge-configuration work. Walk the XDR process ancestry back to that PowerShell execution and determine the exact filename of the script that was run.