Adobe said in an advisory posted on its security website that the vulnerability could allow attackers to gain control of affected computer systems. It released updates to fix the bug for systems running on Microsoft Corp's Windows, Apple Inc's Mac and Linux operating systems.

Moscow-based Kaspersky Lab said on its blog that it learned in mid-April that a Syrian Justice Ministry website,, that serves as an online forum for citizen complaints had been compromised. No attacks on other websites have been reported as a result of the Flash bug.

"We believe the attack was designed to target Syrian dissidents complaining about the government," Kaspersky Lab researcher Vyacheslav Zakorzhevsky said in the blog post.

Kaspersky described the attack as a "watering-hole" campaign. In such attacks, hackers infect websites frequented by individuals whose computers they are looking to compromise. When they visit the tainted site, their systems become infected.