The Russia-linked hackers behind last year’s compromise of a wide swath of the U.S. government and scores of private companies, including SolarWinds Corp., have stepped up their attacks in recent months, breaking into technology companies in an effort to steal sensitive information, cybersecurity experts said.

In a campaign that dates back to May of this year, the hackers have targeted more than 140 technology companies including those that manage or resell cloud-computing services, according to new research from Microsoft Corp. The attack, which was successful with as many as 14 of these technology companies, involved unsophisticated techniques like phishing or simply guessing user passwords in hopes of gaining access to systems, Microsoft said.

Source: In a recent blog post to the company’s website, Microsoft’s corporate vice president of customer security and trust, Tom Burt, wrote that “state actor Nobelium has been attempting to replicate the approach it has used in past attacks by targeting organizations integral to the global IT supply chain.”

Nobelium is “attacking a different part of the supply chain: resellers and other technology service providers that customize, deploy and manage cloud services and other technologies on behalf of their customers,” according to the company.

Burt wrote that 609 Microsoft customers had been informed that they’d been attacked between July and October of this year close to 23,000 times “with a success rate in the low single digits.”

The attacks, according to the executive, were not aimed at a specific flaw in any of the systems, rather, they were “password spray and phishing” attacks, which are aimed at stealing credentials that grant the attackers access to privileged information.

The Russian state-backed hacking group is, according to Burt, “trying to gain long-term, systematic access to a variety of points in the technology supply chain, and establish a mechanism for surveilling – now or in the future – targets of interest to the Russian government.”