Inside the Mind of a Red Teamer: A Realistic Attack Simulation | Cyber Codex

Every breach begins as a whisper in the dark before it turns into a storm.

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The Scene

• It’s 3:07 AM. Inside TechForge Corp’s SOC, a junior analyst yawns at a flood of PowerShell alerts scolling across the SIEM dashboard. He dismisses them as yet another false positive. What he doesn’t realize is that a Cobalt Strike beacon has already checked in from an internal host. WIthin two hours, Domain Admin is comrpomised, and encrypted engineering blueprints are quietly exfiltrated over HTTPS.

• This isn’t fiction. It’s a red team simulation inspired by SolarWinds, Hafnium’s ProxyLogon campaigns, FIN7’s persistence playbooks, and APT29’s stealth exfiltration. In this write-up , I’ll walk you through a realistic end-to-end attack chain with real-world CVEs and MITRE ATT&CK techniques, demonstrating how attackers quietly dismantle enterprise defenses — and how defenders could have crushed me at every step.

The Target Environment

For realism, I built a lab modeled after a mid-sized enterprise:

• A hybrid environment with on-prem Active Directory integrated with Azure AD.

• Public-facing assets: Outlook Web Access, Citrix portal, and a VPN concentrator.

• Developers with elevated permissions for internal CI/CD pipelines.

• Security stack: EDR deployed on endpoints, centralized SIEM with log aggregation, perimeter firewall with IDS signatures, and email gateway filtering.

• High-value target: Encrypted intellectual property files stored on a protected file server.

TechForge, like many real-world organizations, has invested in security products but lacks attack path visibility. That’s what this engagement exposed.

Phase 1: Recon — Ghosting in Plain Sight (MITRE: T1595, T1592, T1589)

• Before launching a single exploit, I spent days gathering intelligence silently.

• I started by enumerating their external attack surface using Amass and Sublist3r, uncovering forgotten subdomains such as legacy.techforgecorp.com. A quick review of SSL/TLS certificates on crt.sh revealed additional internal services.

• Next, I performed open-source profiling of TechForge employees. LinkedIn posts revealed usernames, project names, and technology stacks. GitHub commits by developers referenced outdated Jenkins jobs, giving hints about internal repos.

• Credential leaks were the jackpot: searching breach dumps on HaveIBeenPwned revealed corporate credentials exposed in a 2019 third-party breach. Combined with Shodan scans, I confirmed that the organization hosted a Microsoft Exchange 2016 server exposed to the internet.

• These tactics closely mirror the recon playbooks of SolarWinds attackers, who spent months mapping their target environments before moving.

• Defensive takeaway: Conduct external asset monitoring and threat intelligence scans on yourself. Treat OSINT like an attacker would.

Phase 2: Initial Access — Exploiting ProxyLogon (MITRE: T1190, T1078)

• The unpatched Exchange server became my doorway. I confirmed it was vulnerable to CVE-2021–26855 (ProxyLogon) using nmap --script vuln and a custom Python script. Chaining this with CVE-2021-27065 allowed me to achieve remote code execution on the server.

• Within minutes, I dumped all mailboxes using ewsmanage, harvesting sensitive communications that could fuel phishing campaigns or help me understand organizational structure.

• This phase mirrored Hafnium’s exploitation campaign in 2021, where attackers compromised 30,000+ organizations globally by chaining these same vulnerabilities.

• Defensive takeaway: Prioritize rapid patching of internet-facing assets. For critical CVEs, deploy virtual patching via WAF or firewall rules if downtime prevents immediate fixes.

Phase 3: Foothold & Persistence — Becoming a Ghost (MITRE: T1059, T1505, T1547)

• With my initial shell, I needed a way back in if detected. I uploaded a web shell in the /owa/auth/ directory, providing me with persistent remote command execution.

• Then I deployed a Cobalt Strike beacon, tunneling traffic over HTTPS to blend in with legitimate web browsing. To ensure survival, I created a stealthy local administrator account named svc_netlogon and added registry run keys for automatic re-entry.

• These techniques are straight out of FIN7’s persistence playbook, where attackers use a combination of beacons, registry keys, and scheduled tasks to survive system reboots.

• Defensive takeaway: Enable AMSI, script block logging, and EDR alerting on suspicious registry modifications or unusual outbound traffic patterns.

Phase 4: Lateral Movement — The AD Domino Effect (MITRE: T1087, T1075, T1558)

• Once I had a foothold, I pivoted to Active Directory exploitation.

• I ran SharpHound to enumerate user accounts, group memberships, and ACL permissions, feeding this into BloodHound to visualize attack paths. The graph revealed a golden ticket: a service account configured with unconstrained delegation.

• I used Rubeus to extract Kerberos tickets, cracked a service ticket offline, and performed a Pass-the-Ticket attack, granting me Domain Admin rights. Within two hours, I controlled the Domain Controller.

• This is reminiscent of NotPetya’s rapid escalation campaign, which used similar techniques (via Mimikatz) to compromise entire networks in hours.

• Defensive takeaway: Remove unconstrained delegation, enforce service account password rotation, and deploy tiered administrative models to compartmentalize privileges.

Phase 5: Objective Achieved — Stealth Exfiltration (MITRE: T1041, T1071, T1070)

• With full control, I located encrypted engineering blueprints on a network share. To exfiltrate them without tripping alarms, I compressed them with 7zip and used rclone to upload them to an attacker-controlled cloud storage bucket over HTTPS.

• Finally, I cleared local event logs with wevtutil to complicate forensic analysis.

• This “low and slow” approach was inspired by APT29’s stealth campaigns, where attackers exfiltrated sensitive US government data over encrypted channels for months.

• Defensive takeaway: Implement SSL/TLS traffic inspection, data loss prevention (DLP) systems, and strict egress filtering. Anomaly detection on outbound traffic patterns is essential.

The Blue Team Perspective

TechForge’s security stack wasn’t useless — it just wasn’t tuned for advanced threats. The breach succeeded because of:

• Excessive OSINT exposure that made targeted attacks trivial.

• Delayed patch cycles, especially for high-severity CVEs.

• Lack of behavioral analytics to detect stealthy persistence mechanisms.

• Weak Active Directory hygiene, particularly unconstrained delegation and stale service accounts.

• No baseline for outbound traffic patterns, making data exfiltration invisible.

Defense isn’t about buying more tools; it’s about visibility, hygiene, and layered security.

Key Lessons

• Attackers don’t need zero-days to own you. They thrive on misconfigurations, delayed patches, and forgotten accounts. Breaches are often the sum of tiny security gaps chained together.

• The SolarWinds, Hafnium, and NotPetya campaigns taught us that attackers operate like water — they seep through the cracks and spread quietly until it’s too late. Red team simulations like this expose those cracks before real attackers do.

“Breaches aren’t explosions. They’re slow leaks you never notice.”