Banking security firm Trusteer has warned that the infamous information-stealing SpyEye Trojan has expanded its global reach to target even more countries, while adapting its code to circumvent banks’ transaction monitoring systems.

Trusteer chief executive Mickey Boodaei explained in an updated blog post that the majority of botnet activity is aimed at UK and US computers, but that countries including Japan, China and Russia, among numerous others, have been added to the hitlist in the past three months.

SpyEye is often described as a cheaper alternative to ZeuS, but Boodaei explained that it appears to differ in one important way, in that it incorporates new code designed to bypass traditional filters. “Transaction monitoring systems analyse various aspects of the customer’s session with the bank in order to detect abnormal behaviour that may be attributed to malware activity,” he said.