Attackers Are Exploiting Microsoft Teams for Internal Phishing

A new tactic is turning trusted collaboration tools into delivery channels for malicious links and impersonation attempts.

The threat is coming from inside the organization

Microsoft Teams has become a core communication platform for businesses, replacing much of what used to take place over email. But attackers are now using this trust to their advantage—sending phishing links and malicious files from inside Teams itself.

In these attacks, cybercriminals gain access to a legitimate Microsoft 365 account—often through credential theft or infostealer malware—and then use that account to message coworkers through Teams. Because the message comes from a trusted internal user, the link is often clicked without hesitation.

man getting phished by microsoft teams

Why these attacks are harder to detect

Unlike email, Teams messages are not subject to the same filtering or inspection by traditional security gateways. Most organizations trust internal Teams traffic by default. That makes it easier for attackers to deliver malicious payloads or redirect users to fake login pages without triggering alerts.

These messages are often simple: “Can you review this doc?” or “Is this invoice correct?” They rely on speed, familiarity, and the casual tone of chat communication to lower defenses.

What businesses can do right now

Start by treating Micrisoft Teams as an extension of your threat surface. If your organization uses Microsoft 365, verify that Teams is included in your security monitoring stack and that audit logging is enabled.

Security policies should be updated to include messaging platforms—not just email. Users should be trained to question unexpected links or file shares, even if they come from colleagues. Where possible, use conditional access policies to limit risky login behavior, and enable multifactor authentication across all accounts.

While Teams offers productivity benefits, it also creates a pathway for lateral movement once an attacker is inside your environment. Treating chat traffic as inherently trustworthy is no longer a safe assumption.

By Thomas McDonald
Vice President

2025-06-22T16:16:38-05:00May 26, 2025|

QR Code Phishing Is Spreading Across Physical and Digital Channels

A look at how cybercriminals are turning QR codes into credential traps (qr code phishing)—and what businesses can do to reduce exposure.

A familiar tool is being weaponized

QR codes have become a routine part of daily business. They’re used for contactless check-ins, payment processing, document access, and marketing materials. But the convenience that makes QR codes so widely adopted also makes them exploitable.

Threat actors are now embedding malicious links in QR codes—both in emails and in physical materials like posters, mailers, and fake notices. The goal is simple: direct users to a spoofed login page that captures their credentials, often under the guise of document sharing, payment confirmation, or identity verification.

two people scanning qr codes for qr code phishing

What makes QR-based phishing effective

Unlike traditional phishing emails, QR code attacks don’t contain visible links or attachments. Users scan them with personal mobile devices, which often lack corporate security tools. This bypasses many of the protections in place on company-managed desktops and laptops.

Attackers rely on urgency, familiarity, and poor verification habits. A code may appear in a building lobby, a parking ticket, a service renewal notice, or even as a response to a job application. These tactics exploit environments where people are least likely to question what they’re scanning.

How businesses can reduce risk

Organizations should begin by educating staff on QR-related risks. Employees should be taught to avoid scanning codes from unfamiliar or unverified sources, especially those urging immediate action.

IT teams can take further steps by restricting access to personal devices on the corporate network and reviewing how QR codes are used in internal processes, signage, and customer-facing materials.

In environments with mobile device management (MDM), policies can be configured to scan or isolate web activity initiated from QR codes. For highly targeted industries—legal, healthcare, finance—physical security and visual signage policies should be reviewed, especially in shared or public-facing spaces.

The threat is low-tech in appearance but high-impact in execution. Training and operational vigilance are key.

Have questions? Contact us. We’re happy to help.

By Thomas McDonald
Vice President

2025-06-22T15:50:14-05:00May 26, 2025|

Infostealer Malware Is Fueling Business Email Compromise — Here’s What’s Changing

A closer look at how credential theft is reshaping BEC attacks and what businesses need to do now to stay ahead.

Attacks are no longer limited to spoofed emails

Business Email Compromise (BEC) used to rely on tricking users with fake invoice requests or urgent emails from impersonated executives. While those tactics still exist, the landscape is shifting.

Attackers are increasingly using infostealer malware—lightweight programs that quietly extract saved browser credentials, cookies, and tokens. Once installed, even briefly, these tools give attackers access to real email accounts, often without triggering alarms.

The result is a growing wave of BEC attacks that don’t spoof anyone—they use actual inboxes.

infostealer malware stealing data from businessman

What’s happening behind the scenes

Infostealer logs are bought and sold on dark web marketplaces. They include usernames, passwords, session cookies, and autofill data harvested from infected machines—often without detection. Once attackers gain access to a business email account, they monitor conversations, create hidden inbox rules, and impersonate internal stakeholders or vendors to redirect payments or initiate fraudulent transfers. These messages originate from real accounts, making them far harder to detect than traditional spoofing attempts.

Why this matters now

The surge in infostealer use has created a supply chain of compromise: initial infection, credential resale, and ultimately a targeted BEC attack. Many businesses discover the problem only after money is lost, a vendor relationship is damaged, or legal exposure surfaces.

Traditional email security filters don’t stop this. Once credentials are stolen, attackers bypass filtering entirely by logging in directly. While multifactor authentication (MFA) can help, inconsistent enforcement and token-based session hijacking can reduce its effectiveness.

What organizations should do next

Organizations should begin by enforcing MFA across all cloud platforms and user accounts. Endpoint tools should be in place to detect infostealer activity, such as unauthorized file access or suspicious outbound connections. It’s also important to review mailbox rules for any unexpected forwarding or folder manipulation, and to disable legacy protocols like IMAP and POP3, which are often exploited in these attacks.

Teams should also consider monitoring for dark web exposure or working with vendors who alert them when their credentials appear in breach data. The earlier a compromise is detected, the better the chances of avoiding a full-blown attack.

2025-06-22T16:04:22-05:00May 25, 2025|

Actionable Threat Intelligence: What Businesses Should Focus on Right Now

A timely guide to the most pressing cyber threats and how to respond with clarity, speed, and operational readiness.

AI-driven deception is the new frontline

Cyber adversaries are now using generative AI to craft realistic phishing emails, deepfake videos, and voice-based social engineering scams. These tactics are designed to exploit trust and bypass traditional filters.

Businesses should implement advanced email threat protection that uses behavior-based detection, train staff to verify requests through secondary channels, and review voice authentication protocols for sensitive tasks.

a business leader being updated on actional threat intelligence

Infostealers are quietly stealing credentials

Malware strains like Lumma and RedLine are actively stealing browser-stored passwords, email logins, and financial credentials. These tools often remain undetected and are widely sold on underground markets.

Endpoint protection should be configured to detect command-and-control communication and data exfiltration patterns. Credential audits and forced password resets should be scheduled after any suspected compromise.

Ransomware is more targeted—and more public

Double extortion is now standard: threat actors encrypt data, then threaten to release it. This approach is increasingly used against professional services firms, healthcare providers, and mid-sized enterprises.

Organizations must maintain immutable backups, review which systems can communicate laterally across the network, and ensure response plans include legal, public relations, and client communication strategies.

Supply chain attacks remain a blind spot

Third-party vendors continue to be exploited as an entry point into larger organizations. Attackers compromise one supplier and move upstream, making vendor risk management a security priority.

Businesses should maintain inventories of all third-party access points, require vendors to meet minimum security standards, and segment supplier systems wherever possible.

By Thomas McDonald
Vice President

2025-06-22T16:18:19-05:00May 25, 2025|

How to Tell If Your Business Email Has Been Compromised

You may not notice it right away, but when a business email account gets compromised, the damage can escalate quickly. Cybercriminals aren’t always looking to lock you out or cause a scene. Sometimes, they’re happy to quietly monitor your inbox — watching, waiting, and gathering information they can use to exploit your company or your clients.

That’s why it’s critical to recognize the warning signs early. The sooner you know something’s wrong, the faster you can contain the threat, reset credentials, and prevent further damage.

an employee trying to tell if his business has been compromised

Why Email Is a Prime Target

Email is the front door to your business. It’s where invoices are sent, credentials are reset, client conversations are stored, and sensitive documents are shared. That makes it a high-value target for attackers — especially in industries like law, finance, and healthcare.

Unfortunately, most business email accounts (especially those using Microsoft 365 or Google Workspace) can be accessed from anywhere in the world if the credentials fall into the wrong hands. And with phishing kits and credential-stuffing tools readily available online, it’s easier than ever for attackers to break in quietly.

Warning Signs You Shouldn’t Ignore

While every attack looks different, there are a few common red flags that often point to email compromise:

  • You start receiving unexpected password reset requests or MFA prompts

  • Clients or colleagues say they received suspicious emails from your address

  • You see login alerts from unfamiliar locations or devices

  • Emails you never saw are sitting in your Sent or Deleted folders

  • Rules appear in your inbox that forward, delete, or move messages without your knowledge

These subtle signs are easy to miss, especially if your day-to-day email habits don’t change. But they often indicate that someone else has gained access — and may already be using your account as a launch point for further attacks.

What to Do If You Suspect a Breach

If you notice anything out of the ordinary, don’t wait. Start by resetting the account password, removing any unknown forwarding rules, and checking for suspicious sign-in activity. If you use Microsoft 365 or Google Workspace, access the admin center to review login logs and recent activity. It’s also important to notify your IT provider, even if you’re unsure — it’s always better to investigate a false alarm than ignore a real one.

And if your email doesn’t currently have multi-factor authentication (MFA) enabled, consider that a top priority. It’s one of the simplest and most effective ways to stop unauthorized access — even if your password is compromised.

Get a Free Security Check

Worried that your email account may have been compromised — or want help tightening things up before it happens? Cost+ offers a free security check that can identify vulnerabilities, scan for threats, and give you a clear path forward.

Schedule your free check today and take back control of your inbox.

2025-06-22T16:08:48-05:00May 24, 2025|
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