Mobile malware is still statistically tiny compared to threats that target laptop and desktop PCs. But, victims are often detected in Asia, Eastern Europe and Russia, according to security firm F-Secure, which released its mobile threat report in March. Malware embedded in apps often appear in third-party app stores and raise the risk of an infection, according to Mikko Hypponen, chief research officer at F-Secure. Security experts say it is best to avoid downloading any software when traveling abroad. Even software updates to existing applications should be treated as suspect until returning to a trusted location in the United States.