The vulnerability allows attackers to remotely execute a code on an unpatched system that is Remote Desktop enabled, the Ha Noi-based company said.

Microsoft's Remote Desktop Protocol, which is disabled by default on newer Windows installations, allows users to remotely connect to Windows' desktops or servers, and is widely used by enterprises.

Microsoft in March asked system administrators to apply its latest update as a "special priority" given the nature of the flaw, but about one-third of Government web servers in Viet Nam were still vulnerable, BKAV said.

According to the internet security firm, attackers may well develop a code similar to the Morto worm that appeared late last year.

Morto infected machines using RDP and allowed remote attackers to access the file systems of a Windows PC.

"The weak management of server security in governmental organisations is at an alarming level, which could also threaten national security," Nguyen Minh Duc, head of BKAV's internet security department, told Viet Nam News.

BKAV said it had sent warnings to administrators of 520 Government websites ending with.gov.vn.

Virus activity in Viet Nam in June         Quantity

Number of computers infected                 5,701,000

New virus                                                2,983

Internet security in Viet Nam in June Quantity

Number of websites hacked by domestic hackers    11

Number of websites hacked by foreign hackers     175

Total                                                          186

Most rampant viruses in June

1. W32.Sality.PE

2. W32.StuxnetQKY.Trojan

3. W32.StarterYY.Trojan

4. W32.AutoRunUSB.Worm

5. W32.Vetor.PE

6. W32.LnkFakeFolder.Worm

7. W32.Tmgrtext.PE

8. W32.Kawin.Trojan

9. W32.FamonetA.Trojan

10. W32.MalwaresysP.Trojan