Extortion hackers claim to have stolen hundreds of gigabytes of data from a company operating at the legendary New York landmark: the former AT&T building at 550 Madison Avenue.
The Qilin ransomware cartel added 550 Madison to their leak site, claiming they’ve managed to get their hands on a whopping 700 gigabytes of data. However, the Cybernews research team has investigated the claims and has only found five data samples.
According to the team, samples of the data allegedly stolen from the building operator, OAC 550 Owner, include passport photos, incident reports, mortgage assignments, and a service contractor agreement.
As is usually the case with ransomware gangs, threat actors threaten to leak more details if their demands are not met. Affiliates of Qilin, a gang that operates under the ransomware-as-a-service (RaaS) model, often utilize this tactic, too.
We have reached out to the company for a comment and will update the article once we receive a reply.
550 Madison, completed in 1984, was first built to house AT&T headquarters. Later, the building was sold to Sony. Currently, the building is owned by the investment company Olyan.
The landmark building houses the Chub Group, an American-Swiss insurance company, French luxury fashion retailer Hermès, private equity company Clayton, Dubilier & Rice, and other businesses.
The culprit behind the attack, Qilin ransomware, has been steadily growing its influence this year. While the gang has been operating since 2022, it ramped up the volume of attacks in 2025, targeting 68 entities in April alone.
Earlier this week, the gang allegedly breached Asefa, the Spanish subsidiary of France’s SMABPT.
Qilin made headlines earlier this year after taking on SK Group, a global energy and manufacturing giant. According to Cybernews’ dark web monitoring tool, Ransomlooker, the gang has victimized at least 344 companies over the last 12 months.
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