US oilfield services firm Halliburton said an unauthorised third party had accessed and removed data from its systems, providing details regarding the cyber attack in August first reported by Reuters.
The company said it is evaluating the nature and scope of information that was removed, but added that the incident is not reasonably likely to have a material impact.
Halliburton declined to comment in response to Reuters' requests for additional information on the nature of data removed and expenses incurred due to the cyber incident.
It also did not immediately confirm whether it had been contacted by the hackers.
US energy firms have suffered multiple cyberattacks, including ransomware attacks, in recent years.
In 2021, Colonial Pipeline was forced to pay US$4.4 million ($6.6 million) in ransom as its executives were not sure about the severity of the breach.
The incident had caused disruptions and limited access to portions of its business applications, the Halliburton said.
The company activated its cyber security response plan and launched an investigation internally with the support of external advisors to assess and remediate the unauthorised activity once it became aware of the issue, it said.