A cyber spying tool dubbed MiniDuke has been discovered targeting government and critical infrastructures systems.
Secuity firm Kaspersky Labs and Hungarian researchers at Crysys Lab reported unearthing the MiniDuke, which has hit government bodies in Ukraine, Belgium, Portugal, Romania, the Czech Republic and Ireland.
The malware was hidden in corrupted PDF documents, which were used to infect numerous targets.
A research institute, two think tanks and healthcare provider in the US and an unspecified research foundation in Hungary are also thought to have fallen victim to MiniDuke.
The attacks were reportedly targeted with the malicious files masquerading as items such as fabricated human rights seminar information, Ukrainian foreign policy and Nato membership plans.
The file infected machines using a recently discovered PDF exploit in Adobe Reader versions 9, 10, and 11.
The malware lets the hackers carry out several basic actions including copying, moving and removing files, making new directories, activating a kill process and downloading and executing new malware to the machine.
Chief executive and founder Eugene Kaspersky said the malware is notable as it has similar evasion features to older long thought extinct malware variants.
"This is a very unusual cyberattack. I remember this style of malicious programming from the end of the 1990s and the beginning of the 2000s. I wonder if these types of malware writers, who have been in hibernation for more than a decade, have suddenly awoken and joined the sophisticated group of threat actors active in the cyberworld," said Kaspersky.
"These elite, ‘old school' malware writers were extremely effective in the past at creating highly complex viruses, and are now combining these skills with the newly advanced sandbox-evading exploits to target government entities or research institutions in several countries."
Kaspersky reported that it had traced the backdoor connects to two servers, the first in Panama and the second in Turkey.
MiniDuke is one of many cyber spying tools to have been uncovered by Kaspersky in the recent months.
Red October was a global cyber campaign caught targeting numerous European government institutions in January 2013.
The campaign is believed to have stemmed from a Russian-speaking group and been active since at least five years.
Mark Zuckerberg mercilessly trolled by Harvard student newspaper after return to university he dropped out of 12 years ago
'Unauthorised user' blamed by Harvard for insulting Mark Zoinkerberg
Android under attack from 'Judy', Google Play Store malware that has infected up to 36.5 million users
Yet more Android malware discovered on the Google Play Store
Airport believes new system will be more reliable than GPS or Google Maps
OnePlus 3T canned to make way for imminent OnePlus 5 with Snapdragon 835, 8GB memory and dual camera
OnePlus 3T to be prematurely retired on 1 June - perhaps indicating plans for an imminent OnePlus 5 launch