Hong Kong

About one in nine users in Hong Kong, a special administrative region (SAR) of the People’s Republic of China, encounter a malware infection attempt every quarter. Hong Kong has had its share of cyber-crime in the past: Antivirus firm Kaspersky put the country at the 19th most common source of browser-based malware in 2010.

About one in every eight users in Taiwan has had to defend against a malware infection attempt each quarter, according to Sophos. In addition to cyber-crime, Taiwan has become a launching point for many cyber-operations linked to either China or the United States. In 2009, attackers used servers in Taiwan to manage the “Aurora” cyber-attack that stole intellectual property from Google and other technology firms. Certificates used to sign the Stuxnet attack, allegedly developed at least in part by the U.S. government, were stolen from a Taiwanese firm.

About one in every seven users in the United Arab Emirates, the lone country from the Middle East on the Top-10 Riskiest Nations list, run the risk of being infected by malware every quarter. The Middle East has become less a haven for cyber-crime and more a bastion of political hacking between Western and Israeli attackers and Arab nations. In many cases, citizens in the region run a greater risk of being spied on by their government—including the use of commercial Trojans—than being infected by cyber-criminals.

Mexican users run nearly a one in six chance of encountering malware every quarter, according to the Sophos data. Malicious software using the Windows’ Autorun feature, which runs an executable file whenever a device or virtual drive is mounted, is most commonly detected in the UAE and Mexico, the firm said. Microsoft patched Windows in 2011 to reduce the danger of Autorun worms, suggesting that machines continue to be unpatched in countries where the malware is still spreading widely.

Indian users run nearly a one-in-six risk of being infected by botnets and other malware every quarter. Unlike other countries on the list, the country is currently being targeted with variants of the Sality botnet, a family of malicious programs that has evolved into a persistent threat over the past decade. India also took the crown as the top source of spam in 2012, with 12.2 percent of unsolicited e-mail coming from the southeast Asian nation, according to Sophos.

Malaysia has become a popular destination for many U.S. technology firms that are outsourcing manufacturing to nations in Asia. The burgeoning development has also led to an increase in online crime. As in the UAE and Mexico, Autorun viruses are the most common threat, according to Sophos. In 2011, Malaysia-based Digicert, a reseller of SSL certificates, was compromised, leading to the revocation of the firm’s certificates.

Nearly one in five users in the Philippines encounter one or more attempts each quarter to infect their computers. The most common threat for the nation of more than 7,000 islands is a polymorphic virus known as Vetor. In 2012, Philippines national police arrested more than 350 foreign nationals who allegedly had taken part in attacks on banks in China.

A user surfing the Web in the third riskiest online nation, Thailand, has a greater than one-in-five chance of encountering malware each quarter, according to Sophos. The nation, which suffered massive flooding in 2011 that caused a worldwide shortfall in hard-disk drives, has ranked high on lists of most infected countries for more than a year. In April 2011, for example, antivirus firm PandaLabs named it the No. 2 most infected country, with nearly two-thirds of systems infected by some form of malicious software.

Like Thailand, more than one in every five users in China encounter malware each quarter. China is also the country that took the No. 1 spot in PandaLabs’ April 2011 list of most infected countries, with nearly 70 percent of all systems infected with malware. China is also the 12th largest sender of unsolicited email in the world, with 2.7 percent of junk email coming from the country, according to Sophos. No wonder: Microsoft, as part of its investigation into a botnet, found that 20 percent of new computers its employees bought in China were infected with malware and all the computers had suboptimal security settings.

Taking the top slot, the Southeast Asia archipelago of Indonesia has to deal with a digital hot zone: An Indonesian user has nearly a one-in-four chance of encountering an attempt to infect their machine each quarter. Much of the threat is due to widespread Trojan horses, software applications infected with malware that are then sold online according to Sophos. Indonesia is also the 11th largest source of spam in the world, with 2.7 percent of junk email coming from the country, the firm said.