(MENAFN) Several prominent US law firms, including Washington-based Williams & Connolly, have been infiltrated by Chinese hackers, according to reports.

Williams & Connolly informed clients that its systems had been compromised and that some client emails might have been accessed, citing sources familiar with the matter. The firm is renowned for representing high-profile American politicians, including former Presidents Bill Clinton and George W. Bush.

The FBI’s Washington field office is reportedly investigating the breach, along with similar intrusions allegedly carried out by the same group of Chinese cyber actors, which are suspected of targeting more than a dozen other law firms and tech companies in recent months. The FBI has not publicly commented on the investigation.

In a statement, Williams & Connolly said a “small number” of lawyers’ email accounts were accessed via a zero-day attack — exploiting previously unknown software vulnerabilities. “Importantly, there is no evidence that confidential client data was extracted from any other part of our IT system, including from databases where client files are stored,” the firm added. “We have taken steps to block the threat actor, and there is now no evidence of any unauthorized traffic on our network.”

To respond to the breach, the firm has engaged cybersecurity company CrowdStrike and law firm Norton Rose Fulbright to assist in the investigation and mitigation. Preliminary findings from CrowdStrike suggest the attackers are connected to a nation-state actor involved in a broader campaign targeting US law firms and corporations, according to Williams & Connolly.

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