Over practically a decade, the hacker group inside Russia’s GRU army intelligence company referred to as Sandworm has launched some of the most disruptive cyberattacks in history towards Ukraine’s energy grids, monetary system, media, and authorities companies. Signs now level to that very same normal suspect being liable for sabotaging a significant cell supplier for the nation, chopping off communications for hundreds of thousands and even briefly sabotaging the air raid warning system within the capital of Kyiv.

On Tuesday, a cyberattack hit Kyivstar, considered one of Ukraine’s largest cell and web suppliers. The particulars of how that assault was carried out stay removed from clear. But it “resulted in essential services of the company’s technology network being blocked,” in accordance with a statement posted by Ukraine’s Computer Emergency Response Team, or CERT-UA.

Kyivstar’s CEO, Oleksandr Komarov, informed Ukrainian nationwide tv on Tuesday, according to Reuters, that the hacking incident “significantly damaged [Kyivstar’s] infrastructure [and] limited access.”

“We could not counter it at the virtual level, so we shut down Kyivstar physically to limit the enemy’s access,” he continued. “War is also happening in cyberspace. Unfortunately, we have been hit as a result of this war.”

The Ukrainian authorities hasn’t but publicly attributed the cyberattack to any identified hacker group—nor have any cybersecurity corporations or researchers. But on Tuesday, a Ukrainian official inside its SSSCIP laptop safety company, which oversees CERT-UA, identified in a message to reporters {that a} group referred to as Solntsepek had claimed credit score for the assault in a Telegram publish, and famous that the group has been linked to the infamous Sandworm unit of Russia’s GRU.

“We, the Solntsepek hackers, take full responsibility for the cyber attack on Kyivstar. We destroyed 10 computers, more than 4 thousand servers, all cloud storage and backup systems,” reads the message in Russian, addressed to Ukrainian president Volodymyr Zelenskyy and posted to the group’s Telegram account. The message additionally contains screenshots that seem to indicate entry to Kyivstar’s community, although this might not be verified. “We attacked Kyivstar because the company provides communications to the Ukrainian Armed Forces, as well as government agencies and law enforcement agencies of Ukraine. The rest of the offices helping the Armed Forces of Ukraine, get ready!”

Solntsepek has beforehand been used as a entrance for the hacker group Sandworm, the Moscow-based Unit 74455 of Russia’s GRU, says John Hultquist, the top of menace intelligence at Google-owned cybersecurity agency Mandiant and a longtime tracker of the group. He declined, nonetheless, to say which of Solntsepek’s community intrusions have been linked to Sandworm previously, suggesting that a few of these intrusions might not but be public. “It’s a group that has claimed credit for incidents we know were carried out by Sandworm,” Hultquist says, including that Solntsepek’s Telegram publish bolsters his earlier suspicions that Sandworm was accountable. “Given their constant give attention to the sort of exercise, it is exhausting to be stunned that one other main disruption is linked to them.”