The self-styled Caliphate Cyber Army (CCA) took down the website of Sussex-based Solar UK at the end of January, in apparent revenge for a drone strike that killed British hacker Junaid Hussain in Syria.
Hussain was considered a top-notch hacker who was instrumental in radicalizing and recruiting new militants.
Solar UK was just one of several British companies and organizations affected by the retaliation hack. The CCA boasted about its cyberattack in a video published online, where a list of breached targets appeared besides threats and footage of beheadings.
Solar UK's founder Duncan Lee told Sputnik that he did not realize they had been attacked by such a high-profile terror group.
"They replaced our homepage with an Islamic flag and wrote 'hacked by ISIS' [Daesh]," Lee told Sputnik.
"We thought it was interesting and we took it down — it took about two hours."
"We didn't think much of it at the time. It was only when somebody told us that we were in a propaganda video that we understood it really was ISIS."
Mr Lee added that he does not believe his company was singled out for any particular reason.
"It's puzzling. We have no political affiliation: we are a private small firm, working in the renewable sector. The only thing we could think of is that ISIS depends on oil and does not like renewable energy: that could be a spin," Lee told Sputnik.
He also said that although the website does not contain any sensitive data — such as customers' emails, phone number or bank details. Solar UK has scaled up the site's security following the attack.
However, according to an anonymous cyber security source Daesh defacing random websites isn't surprising at all and is actually quite common.
"They do it just because they can. Because these websites have vulnerabilities. They target a random site and say look what we can do because your security isn't good enough. It's nothing personal," an anonymous source told Sputnik.