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New HollowGraph Malware Turns Microsoft 365 Calendars Into a Covert Command Channel

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HollowGraph malware

Malware Finds a New Hideout: Your Work Calendar

A newly discovered strain of malware is doing something that sounds almost too clever to be real: it uses a compromised Microsoft 365 calendar as its command-and-control (C&C) channel. Researchers at Group-IB have named it HollowGraph, and its trick is both elegant and deeply unsettling for any organization that lives inside the Microsoft ecosystem.

The malware doesn’t phone home to some shady server in a far-off data center. Instead, it talks to its operators by reading and writing calendar events on a legitimate business account. The whole thing runs through the Microsoft Graph API, making the malicious traffic look like ordinary Office 365 sync activity.

How HollowGraph Turns a Calendar Into a Dead-Drop

The technique is straightforward in concept but vicious in execution. HollowGraph takes over a victim’s mailbox — in this case, one belonging to an Israeli organization — and uses its calendar as a two-way drop box. Attackers plant new instructions by creating calendar events. The malware, in turn, exfiltrates stolen files by creating its own events with encrypted payloads attached.

These events are dated far in the future — specifically, May 13, 2050. The logic is simple: a calendar event three decades away won’t show up on anyone’s daily agenda. It sits quietly in the background, invisible to the legitimate user, while the malware reads and writes data at will. Payloads are encrypted using a hybrid RSA + AES scheme, so even if someone stumbles onto the event, they can’t read its contents.

HollowGraph supports just two commands: ‘send’ and ‘get’. The ‘send’ command creates a new appointment with an attached file for exfiltration. The ‘get’ command searches for appointments planted by the operator and downloads new instructions. It’s a minimal, purpose-built system — and that’s exactly what makes it hard to spot.

Secondary Channel and Configuration Details

Group-IB found that HollowGraph doesn’t rely solely on the calendar trick. It maintains a secondary communication channel using DNS tunneling to refresh its configuration and update the Microsoft Entra ID (formerly Azure AD) credentials used for authentication. This fallback ensures the malware can still operate even if the primary calendar channel is disrupted.

Upon execution, HollowGraph writes its hardcoded configuration to disk as a file named logAzure.txt. That configuration includes the Entra ID tenant ID, a client ID and secret, the target mailbox address, the C&C domain, and two RSA keys. It’s a complete operational package — the malware never needs to reach out to an attacker-controlled server for initial payload delivery.

Victim Profile: A Focused Campaign, Not a Spray-and-Pray

The evidence points to a narrow, deliberate targeting. Group-IB identified 12 victims, three of which were actively communicating with attacker infrastructure at the time of discovery. The earliest observed communication dates to June 3, suggesting the malware has been operational for roughly six weeks.

Key indicators — including the compromised Israeli mailbox used for exfiltration and malware samples uploaded from Israel — suggest the attackers are laser-focused on Israeli entities. This isn’t a broad, opportunistic campaign. It’s a surgical operation aimed at specific targets.

Attribution: Likely Iran-Nexus, But With Low Confidence

Attribution is always a messy business, and HollowGraph is no exception. Group-IB believes the malware is part of a variant of the Cavern framework, which Check Point detailed earlier this month under the name Cavern Manticore. That framework is linked to an Iran-nexus threat actor.

However, Group-IB is careful to note that it attributes HollowGraph to the Lyceum subgroup (also known as Hexane and SiameseKitten) with low confidence. Lyceum is itself a subgroup of the broader OilRig cluster, which is tied to Iran’s Ministry of Intelligence and Security (MOIS). The researchers found technical similarities — command format, structural patterns — but nothing unique enough for a high-confidence link.

“Based on the evidence currently available, we cannot confidently attribute this activity to any previously identified threat actor,” Group-IB notes in its report. “While these overlaps are noteworthy, they are not sufficiently unique to support a high-confidence attribution.”

What This Means for Defenders

The HollowGraph technique is a reminder that attackers are constantly looking for legitimate services to hide in. Microsoft 365 is so deeply embedded in enterprise workflows that security teams rarely scrutinize calendar API traffic. That’s exactly the blind spot HollowGraph exploits.

For defenders, the key takeaway is to monitor API activity — not just email and file transfers. Anomalous calendar event creation, especially events dated far in the future with unexpected file attachments, should raise red flags. Organizations using Microsoft 365 should also review which applications and service principals have Graph API permissions and audit for any that don’t match known, approved tools.

The days of looking only at network traffic for C&C are long gone. When malware can hide inside your own calendar, the perimeter has moved — and it’s sitting right there in your Outlook folder.

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CyberSecurity

LG to Ban Residential Proxies from Smart TV Apps After Security Study

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residential proxies

Why LG Is Cracking Down on Proxy SDKs

LG Electronics announced this week it will suspend any smart TV apps that turn televisions into always-on residential proxy nodes. The move comes less than a month after researchers revealed that over 42 percent of games and utilities on LG’s webOS store let unknown third parties route internet traffic through users’ TVs.

Security firm Spur published findings in early July showing that residential proxy software development kits (SDKs) have quietly infiltrated smart TV platforms. For Samsung’s Tizen OS, more than a quarter of apps contained similar components. The data suggests a systemic problem, not an isolated incident.

What Are Residential Proxies Doing in Your TV?

Residential proxy networks pay app developers to embed SDKs that turn a device into a proxy node. Paying customers then rent that node to route their own traffic through it. In LG and Samsung smart TVs, Spur found these SDKs bundled with everything from Pac-Man clones to screensavers and file managers.

A Pac-Man app from Bright Data even offers users a choice: watch ads or let the TV serve as a proxy node. Bright Data, which accounted for the majority of proxy SDKs on both platforms, did not respond to requests for comment.

Bright Data and other providers claim they follow rigorous know-your-customer processes to prevent abuse. They also say they deploy countermeasures that stop proxy customers from interacting with other devices on the user’s local network. But critics argue that a one-time consent prompt buried in a TV app is not enough.

LG’s Response: Suspensions and Policy Changes

LG Senior Vice President John Taylor told KrebsOnSecurity that the company is working with developers to remove residential proxy options from their apps. Developers that fail to comply will see their apps suspended.

“A residential proxy network is not an intended use for LG smart TVs,” Taylor said. “LG Electronics is working with developers to remove the residential proxy option from their apps on the webOS platform. If this option is not removed, these apps will be suspended.”

Taylor added that the review is “well underway now.” LG will also strengthen its evaluation process for developer-submitted apps, including those that incorporate proxy SDKs.

The Deeper Problem: Consent and Awareness

Spur’s Trevor Sutter put it bluntly: “A one-time consent prompt buried in a TV app is not a substitute for meaningful transparency, ongoing control, and platform oversight. The risk is amplified when consent comes from individuals within the household who use the device but shouldn’t give consent, such as minors.”

Most consumers do not think of their smart TV as a computer. They don’t audit apps or check for background network activity. That makes residential proxies particularly insidious. The device sits in the living room, always on, always connected — an ideal node for someone who wants to hide their traffic behind a real residential IP address.

Spur’s report notes that the problem is not that residential proxy networks exist, but that they are being embedded at scale in devices that most people cannot easily monitor.

LG’s Other Controversy: McAfee Bloatware

LG’s announcement comes amid criticism over another partnership. This week, the YouTube channel Gamers Nexus showed that certain LG LCD monitors automatically install an app promoting paid McAfee antivirus subscriptions. The app arrives through Windows Update without any approval prompt. Users reported that the software drivers push McAfee promotions without consent, triggering frustration among gamers and professionals alike.

LG has not yet commented on the McAfee issue. But the combination of proxy SDKs in smart TVs and unwanted antivirus promotions in monitors suggests a pattern: LG is comfortable embedding third-party monetization in its hardware, often without clear user consent.

What This Means for LG Users

For now, LG’s crackdown on residential proxies is a positive step. Users should check which apps are installed on their webOS smart TVs and remove any they do not recognize. If an app offers a choice between ads and “network sharing,” the safest option is to uninstall it entirely.

The company says it will continue to review apps and enforce the ban. Whether that translates into real change — or just a temporary PR move — remains to be seen. But for the millions of LG smart TV owners, the message is clear: your television should not be a tool for strangers to hide their internet activity.

As Spur’s research showed, the problem extends beyond LG. Samsung has not announced any similar action for its Tizen platform. Consumers who want to avoid residential proxies altogether may need to look beyond the app store — or consider whether they need a smart TV at all.

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CyberSecurity

CISO Conversations: Andreas Gaetje – Why Business Sense Beats Bit-Crawling in Security Leadership

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Andreas Gaetje CISO

Not Your Typical Hacker Story

Andreas Gaetje won’t pretend he spent his teenage years breaking into systems or writing exploits. He didn’t. The CISO at Körber AG came to cybersecurity from economics and business politics — a route that was unusual in the 1990s and still raises eyebrows today.

“I’m not the deepest bit-crawler,” Gaetje admits. “That’s just not who I am.” And yet, he now leads security for a global technology and manufacturing group with roughly 13,000 employees across 100 locations. Körber’s machines are behind much of the world’s pharmaceutical supply chain. “Probably every vaccine you ever received has been through our machines,” he notes.

His story is a useful counterpoint to the idea that you need to be a hardcore technical wizard to become a CISO. What you do need, Gaetje argues, is a deep understanding of business, the ability to learn constantly, and the trust of the people around you.

From Public Service Dreams to a Consulting Detour

Gaetje didn’t set out to work in security. In the mid-1990s, fresh out of university with a focus on economics and business politics, he expected to land a job in public services. But reality intervened. He needed money immediately, not someday.

The internet was just beginning to transform from an academic niche into a business necessity. Email was becoming the default communication tool. Gaetje made a pragmatic pivot: “I said to myself, Okay, let’s maybe do something in the computer business.”

He joined a consulting firm, hoping to blend his interest in business and technology. But by the early 2000s, he realized that to truly focus on business inside IT, he needed depth in a single sector. He chose finance. “The best industry at that point in time, where IT was really crucial, was the finance industry,” he recalls. He joined an insurance company as an auditor.

The Compliance Era That Changed Everything

Back then, cybersecurity wasn’t the existential business threat it is today. “ITsec and audit had a natural affinity,” Gaetje explains. “ITsec was primarily about compliance — it wasn’t yet the business threat it has since become.” His mix of business knowledge, IT understanding, and audit experience put him in the right place at the right time.

When cybersecurity began to explode as a discipline, he was asked to manage the growing information security function. The real turning point came in the 2010s, with attacks like WannaCry and NotPetya. “It was very clear: we weren’t talking about a simple compliance issue anymore. This was a serious business threat,” he says. “Cybersecurity had become a hot topic. It was complex, innovative, and really interesting to work in.”

By 2018, Gaetje was CISO at Körber IT Solutions. A year later, he took the top security role at the parent company, Körber AG.

Career Advice: Don’t Get Stuck in One SECTOR

Gaetje credits much of his growth to a single piece of advice: if you want to truly understand security, don’t stay too long in one company or one industry. Different sectors have different risk profiles. Stay in one place too long, and your thinking can get rigid. Attackers change fast. You need to be able to change how you think.

“It’s what made me move from the insurance industry into manufacturing and machine building,” he says. “I wanted to learn something else, to experience something new, and do something different.”

What Makes a Security Leader?

Gaetje is blunt about his own leadership style. “I’m not a born leader. I would never consider that,” he says. But he has a clear philosophy: a leader provides direction and a vision of what can be achieved and how. In any group, someone emerges as the de facto leader. The challenge is to justify that dominance with reliability and trust.

“It’s something you can learn,” he insists. “It’s not something that comes out of the blue. I learned and enhanced that learning with training courses. But of course, your personality is also important. You need to be reliable — you need to be a person that people trust, otherwise it just doesn’t work.”

Leadership, Gaetje believes, isn’t limited to formal management titles. “You’re a leader, even if it’s a thought leader driving and directing other people in a specific direction.”

Building a Security Team in a Talent Crisis

The cybersecurity skills gap is well documented — estimates in 2025 ranged from 2.8 million to 4.8 million unfilled positions globally. Gaetje has felt that pressure firsthand. “In recruiting your team, you have a wish list, and then you have reality — and unfortunately, they don’t always fit together,” he says.

But one requirement is non-negotiable: “I need people who want to learn.” The cybersecurity landscape shifts so fast that prior experience matters less than curiosity. “It’s incredible how fast things change. So, what I always need are people who are engaged, can think out of the box, and want to go the extra mile to understand what’s going on.”

Training and career development he can provide. But that initial spark of enthusiasm? That’s on the candidate. “So, whether I’m looking for an engineer, an analyst or some junior position, experience is good, but enthusiasm to learn is necessary.”

Would He Hire a Hacker?

“That depends,” Gaetje says. The hacker mentality — built-in curiosity and persistence — is valuable. But there are two types. “White hackers I would employ; blackhats, no.” He isn’t comfortable bringing someone with a history of malicious activity into Körber.

His advice to ambitious team members is simple: “Be curious. Things are really changing. If you think you know everything about anything, you’re wrong. That’s never true. There’s always something new coming for you to learn and experience.”

AI: The Double-Edged Sword That’s Reshaping Security

Gaetje’s biggest concern today isn’t a specific threat — it’s the sheer speed of technological change. “Just think about the many things you’ve learned in the last few weeks, about new developments, new products and new techniques that have been deployed to the public. AI is an example — we learn new things about the potential of generative AI and agentic AI every week. What used to occur over a period of two years or more now happens in a couple of weeks.”

AI presents a unique challenge because it’s used by both attackers and defenders. Attackers are using it to scale and sophisticate their operations. Defenders are fighting back with their own AI, but those defenses can be manipulated. Meanwhile, shadow AI — systems deployed without IT or security knowledge — is proliferating inside organizations.

“The pace of new technology is truly hard to manage,” Gaetje says. “For each new technology you must find time to learn and understand it — but that’s on top of everything else you’re already doing. And it’s not just you — everyone on your team must find time to understand the new technology, and you must personally motivate them to do so when they are already fully occupied.”

Will AI reduce the need for human security staff? Gaetje doesn’t think so. “I think the role of cybersecurity, and even my own role will be much more important in the future than it is today. But it may change.” As AI spreads across the business, security problems will become too widespread for the security team to handle alone. Other departments — product development, software engineering — will need to be brought into the fold.

The Risk of Losing Core Skills

Gaetje worries that AI could erode foundational skills, especially among programmers and SOC analysts. “AI coding assistants require prompt engineers and architects above programmers — and that can be a problem. How do you bring people from this level to the next level if they are not able to program on their own?”

A similar issue looms for security analysts. The standard view is that AI will collapse the SOC tier hierarchy — no more tier 1 analysts doing triage because AI will handle it. But Gaetje asks: “If the security analyst job can be done via an agentic AI tool, then how will analysts learn how to analyze an event? Maybe in the future, if we just rely on AI, we will lose the ability to see the tricky things in the incident.”

Still, he’s not pessimistic. “I’m pretty sure we will find different ways to handle the changes. And honestly, there’s so much out there that I’m not really concerned that we will lose anything.”

The real challenge, he says, is guiding the security team through this transition. “The job of the security team will change dramatically in the future. That’s my strong belief. The CISO challenge is to help team members along this road to a new level, where they are able to think out of the box to see what else they can bring to the job.”

For more insights from security leaders, check out our other CISO Conversations with Aimee Cardwell and Tarah Wheeler.

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CyberSecurity

AI Attacks Move in Minutes. Here’s How to Build a Defense That Keeps Up.

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The Speed Gap Is Real — and It’s Getting Worse

It used to take an attacker days to craft a phishing lure, identify a target, test it, and move laterally. Now? It takes minutes. Models like Mythos let adversaries automate nearly every step of the kill chain. They write tailored bait, pick the most vulnerable targets, test what lands, and jump to the next host before your team even clears the first alert.

That’s the gap. And it’s not your fault. Most security teams are still running on tools and runbooks built for attackers who work at human speed. But the attackers aren’t human-speed anymore.

So what do you do when the clock is no longer on your side?

Why Traditional Defenses Fall Short Against AI Attacks

The problem isn’t just speed. It’s scale. An AI-powered attack can adapt in real time, shifting tactics based on what it learns from each failed or successful probe. Your average security stack — SIEM, SOAR, EDR — wasn’t designed for that. It was designed for predictable, manual attack patterns.

Think about it. Most incident response playbooks assume a human attacker needs time to pivot. They assume you have minutes or hours to detect, analyze, and respond. That assumption is now dangerous.

A single AI-driven attack can generate dozens of low-level alerts in seconds. Your team drowns in noise while the real threat moves deeper into the network. By the time you realize what’s happening, the attacker — or the AI agent running the attack — is already gone.

What a Modern Defense Needs to Do

To keep up with AI-driven attacks, your defense has to be as fast and adaptive as the offense. That means three things:

  • Automated detection at machine speed. No more waiting for a human to review a log. The system needs to spot anomalies and correlate them in milliseconds.
  • Real-time response orchestration. When an attack is detected, the response — isolating a host, blocking an IP, revoking credentials — should happen automatically, without a human in the loop.
  • Continuous learning. The defense should get smarter with every attack, updating its models to recognize new tactics as they emerge.

This isn’t about replacing your analysts. It’s about giving them a force multiplier that can handle the volume and speed that no human can match.

Join the Webinar: Building a Defense That Keeps Up

On [Date], we’re hosting a live webinar with cybersecurity experts who have been building and testing these systems in real environments. We’ll walk through:

  • How attackers are using AI models like Mythos to accelerate every phase of an attack
  • Concrete examples of AI-driven attacks that bypassed traditional defenses
  • A framework for designing a defense that operates at machine speed
  • Lessons from organizations that have already made the shift

You’ll leave with a clear roadmap for upgrading your security operations to handle the new reality. No fluff. No vendor pitches. Just practical strategies from people who have been in the trenches.

Who Should Attend

This webinar is designed for SOC managers, incident responders, threat hunters, and anyone responsible for keeping their organization safe from advanced threats. If you’ve ever felt like your team is always one step behind, this is for you.

How to Register

Spots are limited. Register for the cybersecurity webinar here to secure your place. You’ll also get access to the recording and slides afterward.

The Bottom Line

AI attacks aren’t coming. They’re already here. The question is whether your defense can keep up. If you’re still relying on playbooks written for human-speed attackers, you’re already behind.

But it doesn’t have to be that way. With the right approach — and the right tools — you can build a defense that moves as fast as the threat. Join us, and let’s figure out how together.

See you there.

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