A hacker group calling itself "Anonymous Malaysia" on Tuesday published a list of 50 Vietnamese websites that it claimed to have controlled and defaced.

In the list published on Facebook and zone-h.org – an archive of defaced websites – there are also websites of Vietnamese educational institutions with “.edu.vn” domains and state agencies such as the Department of Construction of the southern province of Binh Duong and the Phu Tho water supply company.

After purportedly attacking a website, the hacker group left the icon of the notorious Anonymous hacker group and warnings about the security level of the websites.

Foreign security communities said that the move may be retaliation for another attack by Vietnamese hackers on the Football Association of Malaysia website (Fam.org.my) on Monday, and called for all parties involved to show restraint in order to avoid a possible trap set up by any third parties to trigger more aggressive acts from the two sides.

According to an assessment of SecurityDaily.net, most of the websites reportedly attacked are running on Drupal, an open source content management system (CMS) platform.

The group of hackers may have exploited some critical security vulnerabilities in the Drupal platform which were announced earlier this year. The administrators of the websites may have forgotten to update the patches for those vulnerabilities, according to SecurityDaily.net.

However, the vulnerabilities can also be located in the third-party modules that the administrators have already installed.

According SecurityDaily.net, to avoid falling victim to such attacks, especially for those websites running on CMS platforms such as Drupal, Joomla, and Wordpress, the administrators are advised to update to the latest versions, use strong passwords for administration by combining special characters, uppercase letters and numbers, and turn off unnecessary services, modules and plugins.

In addition, the administrators should review their entire website to check if any backdoor has been secretly installed on their system.

Reportedly, there have been attacks on small sites in Vietnam and Malaysia since Vietnam beat Malaysia 2-1 in the first leg of the 2014 AFF Suzuki Cup semifinal in Kuala Lumpur on Sunday. 

Angered by their team’s home defeat, the host attackers used glass bottles, kick, and punches to ‘talk’ with the Vietnamese fans.

Blood was seen on the face and T-shirt of at least one Vietnamese supporter in what the ASEAN Football Federation has described as “the most violent and embarrassing” incident ever recorded in the competition.

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