The high costs and low speeds of hotel Wi-Fi service have long been frustrating for business travelers, but apparently the problems go a lot deeper.

According to the The Wall Street Journal, cybercriminals have been hacking into the computers of executives traveling in Asia using hotel Wi-Fi. Russian cybersecurity company Kaspersky Lab discovered the attacks, which it believes have been happening since 2009 if not earlier. The company released a report on the "Darkhotel" hacking on Monday.

The company believes that the cybercriminals tricked executives into downloading malware through hotel Wi-Fi networks by asking them to download an upgrade to Adobe Flash or Google Toolbar. The hackers then determined whether or not the victim was a significant target and proceeded to transfer more malware that grabbed cached and saved passwords.

The report did not name any specific hotels or individuals that were victim to Darkhotel, but it did note that about two-thirds of the attacks occurred in Japan. It is unclear why these specific executives were being targeted, but the cybercriminals knew the targets' travel details, including their expected arrival and departure times, room number, and full names, before starting the attack.

Because of the sophistication of the attack, Kaspersky Lab believes that a government, rather than individual hackers, may be responsible. The malware has two Korean-language characters in its code, but Kaspersky was unable to pinpoint an exact suspect.

The FBI issued a similar warning in 2012, but didn't specify a country where the attacks originated. The warning urged business travelers to be extra careful when downloading software updates.