Suspected Russian hackers targeted the cybersecurity company Malwarebytes Inc in the course of a sprawling cyberattack that targeted US government agencies and companies.

The attacker abused “applications with privileged access to Microsoft Office 365 and Azure environments”, according to a Tuesday blog post by chief executive officer Marcin Kleczynski. He said the attack was part of the same hacking campaign that has utilised infected software from SolarWinds Corp to target other organisations.

“After an extensive investigation, we determined the attacker only gained access to a limited subset of internal company emails. We found no evidence of unauthorised access or compromise in any of our internal on-premises and production environments,” Kleczynski wrote.

On Dec 15, Microsoft alerted Malwarebytes about “suspicious activity from a third-party application” that was consistent with the behaviors of the SolarWinds’s attackers.

This incident is the latest example of the attackers targeting security companies in the course of the hacking campaign. They stole tools from the firm FireEye Inc and attempted to breach Crowdstrike Inc through similar tactics they used against Malwarebytes.

“These attackers were clearly sophisticated and primarily targeted federal agencies and security companies, as far as I’m aware,” Kleczynski said in an email to Bloomberg News.

FireEye’s investigation into its own breach last month revealed that the hackers had installed malicious code into SolarWinds’s Orion software, which is used by government agencies and Fortune 500 companies. The malicious code, which customers received by updating the software, provided a launching pad of sorts for further attacks by the hackers into computer networks.

According to SolarWinds, as many as 18,000 of its customers may have received infected updates, though the hackers are believed to have conducted further intrusions in far fewer of them. Malwarebytes isn’t a SolarWinds customer.

 - Bloomberg