Spanish telecommunications giant Telefonica recently fell victim to a significant cybersecurity breach, showing that even large organizations can be vulnerable. The event highlights how important it is to maintain strong defenses, especially against infostealers, which are designed specifically to steal information.

The Breach: What Happened?

This month (January 2025), Telefonica confirmed unauthorized access to its internal Jira ticketing system. The breach, orchestrated by a group of attackers allegedly linked to the Hellcat ransomware group, resulted in the theft of approximately 2.3 GB of sensitive data. The stolen information included:

• 24,000 employee emails and names
• 500,000 Jira issues and summaries
• 5,000 internal documents
• 236,493 lines of customer data

The Attack Vector: Infostealer Malware

The breach was facilitated by infostealer malware, a type of malicious software designed to harvest sensitive information such as login credentials from infected devices. Numerous employees were reported to be compromised, providing attackers with critical credentials for initial access

• 469 employee credentials on Telefonica’s domain were compromised.
• 469 employee credentials on Telefonica’s domain were compromised.
• 469 employee credentials on Telefonica’s domain were compromised.
• 469 employee credentials on Telefonica’s domain were compromised.

One of the biggest misconceptions in modern cybersecurity is that monitoring internal systems is all it takes for a secure environment. While this might have been a sound approach years ago, the modern supply chain consists of dozens of interconnected entities, where a single weak link can can bring down the entire system.

Former U.S. Air Force intelligence analyst, Crystal Morin, warns that sophisticated attacks leveraging technologies like large language models (LLMs) will likely escalate, particularly targeting supply chains with spear phishing attacks designed to steal vendor credentials.

While you can’t directly control what your vendors do regarding their cybersecurity, proactively monitoring their credentials on the dark web can prevent compromised access from becoming your problem.

How compromised vendor credentials impact your business

Your business doesn’t operate in isolation. Vendors, suppliers, and third-party partners form an intricate web of dependencies that keep operations humming along. But this interconnectedness comes with a cost: when a vendor’s credentials are compromised, the fallout can ripple through the supply chain and hit your business hard.

If a vendor with privileged access to your systems gets breached, attackers can waltz right into your environment, bypassing even the most robust internal defenses. This could mean stolen customer data, disrupted operations, or even ransomware locking up critical systems. all because of a weak link you don’t directly control.

The financial impact can be substantial, taking into account losses from downtime, recovery, and potential legal fees or regulatory fines.

Beyond the dollars and cents, there’s the operational chaos. A vendor breach could halt production lines, delay shipments, or cripple customer-facing services, leaving your business scrambling to pick up the pieces. And in a world where reputation is everything, the public exposure of a breach tied to your supply chain can paint your brand as careless or unprepared, even if the fault lies elsewhere.

How to actively monitor vendor credentials

When vendor credentials leak, they don’t always reach the attacker right away. They often circulate quietly on the dark web, passing through hands until they land with someone ready to act. The only solution and the key to preventing vendor-related breaches is to know that there is a compromise before it’s too late. 

By actively monitoring your vendors on dark web marketplaces, forums, and hidden communities, your organization can swiftly identify compromised credentials and take immediate corrective action.

Twilight Cyber empowers your organization with real-time insights and actionable intelligence into infected machines and credential exposure through dark web activity, to secure your supply chain from vendor-related cyber threats.

Twilight Cyber’s Identity Threat Protection platform provides:

• Real-time dark web surveillance for infected machines and stolen or leaked vendor credentials.
• Immediate alerts and actionable intelligence when credentials appear online.
• Actionable insights that enable proactive mitigation in response to identified threats.

Building a vendor monitoring maturity curve

To start effectively managing your third-party risk, you can implement the following approach: 

Step 1: Baseline Risk Mapping

Begin by identifying which vendors have access to your sensitive systems or data. Categorize them by access level and business criticality. This risk map helps you prioritize who needs closer monitoring based on their potential impact.

Step 2: Continuous Dark Web Surveillance

Once your high-risk vendors are identified, integrate Twilight Cyber’s dark web monitoring service to track exposed credentials in real time. Our platform scans underground marketplaces, data dumps, and hacker forums for infected machines and stolen data so you don’t have to. You’ll receive immediate alerts when a match is found, usually within hours of initial infection.

Step 3: Actionable Intelligence & Response Playbooks

Each alert includes actionable context, including what was exposed, where it was found, and how to respond. Use this intelligence to trigger a predefined response: rotate affected credentials, notify vendors, or restrict access as needed. The faster you act, the less damage done. 

Which vendor accounts should you monitor

With so many vendors, it’s impossible to track everyone. When deciding which vendors to monitor, always prioritize your critical and high-risk vendors. Those are the ones with access to your most sensitive systems or data. 

Lower-risk vendors might still hold the keys to something important, so consider monitoring them too if they’re part of your core operations.

Here are the types of vendor accounts you should look out for:

Accounts with Privileged Access

Any vendor account with elevated permissions deserves special attention. This includes accounts with admin rights, access to financial transactions, or control over critical infrastructure. These are the “master keys” to your business, making them prime targets for attackers. Constant vigilance here is non-negotiable.

Accounts Tied to Core Operations

Vendors that manage essential functions like IT services, logistics, or production are also critical to your business. Even if they don’t handle sensitive data, a breach in these accounts could disrupt everything. Monitor them to avoid a domino effect that brings your operations to a standstill.

Start monitoring vendor exposure now

Ready to take full control of your security? 

Twilight Cyber’sreal-time identity threat protection detects and neutralizes compromised machines and credential leaks within hours of a breach, with zero installation required.

Contact Twilight Cyber today and start proactively securing your vendor network against threats.

Spanish telecommunications giant Telefonica recently fell victim to a significant cybersecurity breach, showing that even large organizations can be vulnerable. The event highlights how important it is to maintain strong defenses, especially against infostealers, which are designed specifically to steal information.

The Breach: What Happened?

This month (January 2025), Telefonica confirmed unauthorized access to its internal Jira ticketing system. The breach, orchestrated by a group of attackers allegedly linked to the Hellcat ransomware group, resulted in the theft of approximately 2.3 GB of sensitive data. The stolen information included:

• 24,000 employee emails and names
• 500,000 Jira issues and summaries
• 5,000 internal documents
• 236,493 lines of customer data

The Attack Vector: Infostealer Malware

The breach was facilitated by infostealer malware, a type of malicious software designed to harvest sensitive information such as login credentials from infected devices. Numerous employees were reported to be compromised, providing attackers with critical credentials for initial access

• 469 employee credentials on Telefonica’s domain were compromised.
• 469 employee credentials on Telefonica’s domain were compromised.
• 469 employee credentials on Telefonica’s domain were compromised.
• 469 employee credentials on Telefonica’s domain were compromised.

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