Louis Michael Gaebler, 23, and Ruben Ian Thomson, 21, are accused of being members of a group that allegedly infected thousands of organisations with malicious software code for illegal profit.
"The malware itself was inserted like the Trojan horse into trusted software," Australian Federal Police Commander Graeme Marshall told reporters on Thursday.
This allegedly enabled large-scale cybercrime offending, including data intrusion, identity crime, and cryptocurrency-based money laundering.
"The infected software was incorporated into the computer systems of victim organisations," Commander Marshall said.
"It enabled the syndicate to harvest credentials, sensitive data, and authentication materials."
Commander Marshall said it was "rare to have cyber criminals of this status domestically".
The group known as Team PCP allegedly impersonated legitimate identities and online services, bypassed security controls, and gained unauthorised access to networks and cloud environments.
Investigators believe the malicious code infected more than a thousand organisations in the government, academic, and corporate sector.
This group allegedly stole more than half a million credentials and illegally harvested at least 300 gigabytes of data.
"The impact is extensive, and to date, the financial impact includes global remediation costs for victim organisations, estimated to be in the hundreds of millions of dollars," Commander Marshall said.
Gaebler and Thomson were arrested on Wednesday night after AFP, US Federal Bureau of Investigation and WA Police officers raided three properties in Perth, following a joint investigation.
Thomson, who is accused of leading the outfit, was charged with eight offences, including four counts of unauthorised modification of data with intention to commit a serious offence.
Gaebler is facing six similar charges.
The duo appeared in Perth Magistrates Court on Thursday, where their cases were adjourned for mention on September 18.
Thomson attempted to apply for bail, but the application was withdrawn when the magistrate told the court she would not grant it because there was no way to prevent him from using a computer to tamper with online evidence.
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