The Chat Trap: A Red Team’s Path to Domain Compromise

It all began a few months ago with what appeared to be a straightforward objective: assess the security posture of several websites.

The scope? Black-box testing across multiple domains. No insider information, no credentials just the internet, a browser, and a healthy dose of curiosity.

At first glance, it resembled a standard reconnaissance engagement. But, as is often the case, things escalated quickly. What started as a routine assessment evolved into a full-scale digital treasure hunt complete with phishing, cookie theft, VPN maneuvering, and an unexpected journey to the core of the domain.

Like any well-executed digital operation, it all started with a map.

The initial phase involved scanning the landscape: domains, subdomains, and anything with an IP address and a dream of being online. Everything proceeded smoothly. Reconnaissance was clean, targets were identified, and the outlook was optimistic.

However, after several days of probing, scanning, and politely knocking on digital doors, the results were underwhelming. No remote code executions, no exposed admin panels, not even a forgotten development portal whispering secrets. Just a series of hardened surfaces and a chorus of polite 403s.

It began to seem like the environment might actually be secure.

Spoiler: it wasn’t!

The Bot That Spilled the Beans

A specific URL stood out during reconnaissance. The associated web page featured a chatbot designed to provide information about open tickets, but only to authenticated users. One notable behavior was observed: when attempting to check a ticket, the chatbot would prompt for a username. If the username did not exist, it would respond with a message indicating that the user could not be found.

This behavior revealed a potential for user enumeration. Once the username format was understood, it became clear that the chatbot could be queried in a way that mimicked legitimate requests. Because the chatbot responded differently based on whether a username existed, it effectively acted as an oracle leaking information that could be used to validate user identities.

At this point, automation was introduced. A Python-based bot was developed with a single purpose: interrogate the chatbot and determine which usernames were valid based on its responses.

With the username format already identified, a custom wordlist was generated using common surnames to ensure realistic input. The bot sent queries, analyzed responses, and quietly compiled a list of valid users “one polite chatbot conversation at a time”.

What began as a subtle behavioral quirk evolved into a full-scale enumeration engine.

The bot operated continuously, logging and analyzing each interaction. Every nuanced response helped confirm whether a username was valid or not. The objective was to build a clean, reliable list of active accounts, data that could support further phases such as phishing, password spraying, or impersonation. It was akin to assembling a digital phonebook.

This simple observation turned into a strategic advantage. By chaining together behavioral inconsistencies and leveraging automation, it was possible to extract meaningful intelligence from a system never intended to reveal it.

After a few days of probing, the enumeration process yielded some valid usernames. This confirmed the viability of the approach and demonstrated that the chatbot’s behavior could be exploited to extract sensitive user information without triggering alerts.

With a verified list of usernames in hand, the next logical step was to assess whether this intelligence could be operationalized. A review of the engagement scope confirmed that phishing was permitted.

With that green light, the operation shifted gears. The usernames were no longer just data points they were now viable targets. The next phase was set to begin.

Operation Fisherman

With a list of usernames in hand and curiosity at full throttle, the next phase involved deeper reconnaissance. Due to the absence of restrictions on Microsoft Teams federation, it was possible to passively gather intelligence through the platform. While not literal eavesdropping, Teams proved to be a goldmine of information.

By exploring available profiles and interactions, it was possible to extract full names, job titles, and alternate email addresses often revealed through automated out-of-office replies. These seemingly minor details provided valuable insights into team structures and departmental roles.

Armed with this information, phishing messages were crafted with a high degree of personalization, so tailored they practically wore name tags.

The next step was to design the bait. Using the collected data: names, roles, email patterns, and the organization’s branding style, a convincing phishing email was created. The message announced a mandatory privacy policy update. It was clean, official-looking, and just mundane enough to avoid suspicion. The kind of email that gets clicked without a second thought.

It had all the right ingredients: urgency, authority, and a link that led directly into a trap.

To enhance credibility, a domain was registered that closely resembled the legitimate one, differing by only a subtle variation (e.g., replacing .com.br with .net.br). This minor change was easy to overlook but effective in maintaining the illusion of authenticity. Combined with the polished message, it created a near-perfect impersonation of internal communication.

An Evilginx infrastructure was deployed on the spoofed domain, enabling the proxying of the legitimate login page and the capture of session tokens. This setup allowed for the bypassing of multi-factor authentication (MFA).

The phishing email included a call to action, prompting recipients to review and acknowledge a “mandatory update” to the privacy policy. To increase engagement, the message emphasized urgency and potential consequences for non-compliance, such as restricted access to internal systems. This pressure-based tactic significantly boosted interaction rates and mirrored real-world techniques used by threat actors.

If you’re not familiar with Evilginx, it’s a man-in-the-middle attack framework used to phish login credentials along with session cookies — effectively allowing the bypass of two-factor authentication (2FA). It’s widely used by red teams, penetration testers, and threat actors alike. Check out Kuba Gretzky’s repository for more details: https://github.com/kgretzky/evilginx2

After setting up the Evilginx infrastructure, the next phase focused on establishing credible sender identities. To achieve this, fake Outlook accounts were created to impersonate members of compliance and policy teams. Outlook.com was specifically chosen as the email provider due to its trusted domain reputation, which reduces the likelihood of messages being flagged or blocked by common email security solutions. This significantly increased the chances of successful delivery and user interaction. The combination of a familiar sender name, a reputable domain, and a carefully crafted message resulted in a highly convincing phishing scenario that blended seamlessly into internal communication flows.

With all components in place, the phishing campaign was launched, targeting previously identified users. Within minutes, the Evilginx panel began receiving responses, and credentials started coming in almost immediately. After a few emails sent, five accounts were successfully compromised “a notable success rate for a targeted phishing operation”.

What stood out most was the profile of the compromised users. Among them two were system administrators and one C-level executive in the IT department. This level of access represented a significant escalation opportunity, as these accounts typically possess elevated privileges and broader visibility across the infrastructure.

With the phishing campaign yielding results, session cookies were exported and used to authenticate into the compromised accounts. Access was successfully obtained to the users’ Microsoft 365 environments, including email, OneDrive, SharePoint, and Teams.

The next step involved exploring potential access to cloud infrastructure, particularly Azure resources, through the compromised accounts. However, after a thorough review, no direct access was found to cloud-hosted virtual machines or applications that would allow shell access or command execution.

The key under the doormat

Despite the lack of shell access, the compromise was far from fruitless. A wealth of sensitive documentation was uncovered, including:

• Network diagrams and topologies
• Internal project plans and timelines
• Configuration files and deployment procedures
• Lists of internal systems and IP ranges

This information provided deep insight into the infrastructure, significantly lowering the barrier for future lateral movement or privilege escalation. Even without direct command execution capabilities, the intelligence gathered at this stage was invaluable for mapping the environment and planning subsequent actions.

After several hours of combing through the compromised users’ files, a particularly sensitive OneNote notebook surfaced. Buried among routine meeting notes and project outlines was a page with an unassuming title but its contents were anything but. Inside was a trove of credentials.

Among the various usernames and passwords listed, one entry stood out: credentials for a local administrator account on the domain controllers.

This marked a pivotal escalation point. With these credentials, a direct path to the core Active Directory infrastructure was now available potentially granting full control over the domain environment.

To validate the credentials, access to the internal network was required. Earlier reconnaissance, particularly firewall enumeration efforts, had already identified the VPN solution in use.

The appropriate VPN client was downloaded and installed. The final hurdle was multi-factor authentication (MFA), which was required to complete the VPN login process.

Fortunately, this had been anticipated. During access to the compromised Microsoft 365 accounts, it was observed that the MFA mechanism delivered one-time PINs to the users’ Outlook inboxes. With full mailbox access, these codes were retrieved in real time, allowing the VPN authentication process to be completed without triggering any alerts.

With the VPN connection established and MFA bypassed, access to the internal network was achieved. The final step was to validate the domain administrator credentials.

An RDP session was initiated to one of the Domain Controllers using the local admin credentials retrieved from the OneNote file. As expected, the login was successful.

At this point, a critical objective had been achieved: direct access to a Domain Controller. This level of access represented complete domain compromise, confirming the effectiveness of the phishing campaign and the post-exploitation strategy.

What We Learned and Why It Matters?

This episode highlights a critical reality: phishing is still alarmingly effective, even after more than 25 years of widespread use. It’s easy to underestimate its impact, many including myself, believed that phishing was more of a nuisance and trivial than a serious threat. That perception changed completely after seeing its effects from the other side.

Phishing is an extremely serious attack vector. Its consequences can be catastrophic, leading not only to financial and intellectual property losses but also, in some cases, to human harm.

The FBI’s Internet Crime Complaint Center (IC3) reinforces this concern in its 2024 Internet Crime Report. The report reveals a sharp rise in cybercrime, with 859,532 complaints filed and over $16 billion in reported losses a 33% increase from 2023. Among the most reported crimes were phishing/spoofing, extortion, and personal data breaches. Notably, investment fraud especially those involving cryptocurrency accounted for more than $6.5 billion in losses, making it the most financially damaging category.

In this particular scenario, the outcome was relatively controlled: a report outlining the identified vulnerabilities and a workshop focused on phishing awareness and prevention strategies for both enterprise and personal environments. But imagine if this operation had been carried out by a threat actor or an advanced persistent threat (APT) group. The consequences could have been far more severe ranging from data theft and financial loss to long-term infiltration and operational disruption.

In the end, this wasn’t just a technical exercise it was a wake-up call. The path from a chatbot quirk to full domain compromise didn’t require elite exploits or nation-state resources. It took patience, creativity, and a deep understanding of how people and systems interact. Phishing, often dismissed as old-school, proved once again that it remains one of the most effective tools in the attacker’s arsenal. The difference between a red team report and a real-world breach is often just intent. This time, it ended with a debrief and a workshop. Next time, it could be ransomware, data theft, or worse. Security isn’t just about firewalls and patches it’s about vigilance, awareness, and never underestimating the basics.