The Largest Cyber Breaches of 2023

And How They Could've Been Avoided

As technology continues to advance, so do the tactics of cybercriminals seeking to exploit vulnerabilities for their gain.

In 2023, many high-profile organizations fell victim to cybersecurity breaches, exposing sensitive data and highlighting the pressing need for robust security measures. In this blog post, we delve into five major incidents. We'll explore how these breaches occurred, their impact, and how they could have been prevented.

1. Royal Mail LockBit Attack

How it Happened: The Royal Mail LockBit attack involved a sophisticated ransomware strain that targeted the UK's postal service. The attackers likely gained initial access through a phishing email, exploiting employee trust and leveraging social engineering techniques to spread the ransomware across the organization's network.

Impact: Critical systems were encrypted, disrupting mail delivery operations and causing significant delays. The attackers demanded a substantial ransom in cryptocurrency for the decryption key, adding financial strain to the already compromised Royal Mail. While the Royal Mail refused to pay the nearly $80 million ransom, they've reportedly spent over $10 million in post-breach ransomware prevention.

Attackers: The LockBit ransomware attack was attributed to an underground hacking group that identified themselves as the "PostalPhantoms."

Prevention: Regular employee training on recognizing phishing attempts, email filters and flagging software, and implementing multi-factor authentication could have mitigated the risk of such an attack.

2. T-Mobile Attack

How it Happened: T-Mobile, a major telecommunications company, experienced a data breach that exposed sensitive customer information. The attackers exploited a misconfigured server, gaining unauthorized access to a vast database of customer records.

Impact: Personal data, including names, addresses, and phone numbers, were compromised, leading to identity theft concerns for 37 million T-Mobile customers. The breach resulted in reputational damage and potential legal consequences for the telecommunications giant. In addition, the company disclosed a follow-up breach that took place only a few months later, further exposing T-Mobile customers and staff to potential fraud or phishing attacks.

Attackers: The identity of the attackers remains unknown, with the investigation ongoing at the time of writing.

Prevention: It took T-Mobile two months to detect the breach, giving the attackers ample time to pivot within the network and exploit the data before users were warned. Routine security audits, comprehensive system monitoring, and promptly addressing misconfigurations could have thwarted the attackers' attempts to exploit vulnerabilities.

3. City of Oakland Ransomware Attack

How it Happened: The City of Oakland fell victim to a ransomware attack that encrypted crucial municipal systems. The attackers likely gained access through a phishing email or a compromised third-party vendor, exploiting vulnerabilities in the city's network.

Impact: Over a decade's worth of sensitive data was stolen, including police data. Essential services were disrupted, affecting residents and businesses. The attackers demanded a ransom in exchange for the decryption key, putting additional strain on the city's budget. Oakland declared a state of emergency and was forced to close many government buildings.

Attackers: Attribution was challenging, but cybersecurity experts speculated the involvement of a ransomware-as-a-service (RaaS) group known as "CryptorCrew."

Prevention: Enhanced email security protocols, regular vulnerability assessments, and a robust backup strategy could have minimized the impact of the ransomware attack.

4. MOVEit Attack

How it Happened: MOVEit, a secure file transfer solution, experienced a breach that exposed sensitive data impacting thousands of organizations around the world. The attackers exploited a zero-day vulnerability in the software, gaining unauthorized access to confidential information.

Impact: Sensitive data, including financial records and intellectual property, were compromised, leading to potential legal ramifications and damage to MOVEit's reputation. Due to MOVEit's integration with other companies, it's believed that the MOVEit breach was only the tip of the iceberg, and that many of their customers were targeted as a consequence.

Attackers: The attack was conducted by the notorious Clop ransomware group, a Russian-speaking group who've extorted over $500 million in recent years. Lately, they've adopted an encryption-less extortion technique. Rather than encrypting victim data, they simply threaten to release it if not paid.

Prevention: Rapid response to zero-day vulnerabilities, Bug Bounty programs, regular software updates, and threat intelligence sharing could have reduced the risk of exploitation.

5. MGM Resorts Attack

How it Happened: MGM Resorts, a prominent hospitality and entertainment company, faced a data breach that exposed the personal information of guests. The attackers exploited vulnerabilities in the company's network, potentially gained through a compromised third-party service.

Impact: Guest data, including names, addresses, and payment card information, were compromised, leading to financial losses and reputational damage for MGM Resorts. MGM lost an estimated $100 million as a direct result of the attack.

Attackers: The ALPHV/BlackCat gang was behind the attack. A similar attack took down Caesars just a few days later.

Prevention: Enhanced third-party vendor security assessments, regular network penetration testing, and encryption of sensitive data could have fortified MGM Resorts against the attack.

Other Major Attacks

  • The British Library: The Rhysida ransomware group stole and leaked internal HR data.

  • 23andMe: Sensitive ancestry and personal data were stolen from 6 million users.

  • KNP Logistics Group: A major logistics firm was forced to shutter their business after a ransomware attack made fundraising impossible.

  • Chinese espionage: Microsoft disclosed successful breaches by Chinese actors who accessed emails by US government employees.


The cybersecurity breaches of 2023 underscore the critical importance of proactive security measures in an increasingly digital world. The cost of inaction is simply too high. Act today to protect your organization and customers. Organizations must prioritize employee training, regularly assess and update their systems, and collaborate with the broader cybersecurity community to stay ahead of emerging threats. Learning from these incidents, businesses can fortify their defenses and protect against the ever-evolving landscape of cyber threats.

About Silent Breach: Silent Breach is an award-winning provider of cyber security services. Our global team provides cutting-edge insights and expertise across the Data Center, Enterprise, SME, Retail, Government, Finance, Education, Automotive, Hospitality, Healthcare and IoT industries.