In the past year, federal prosecutors and FBI agents have increased their efforts to defeat botnets and contain malware outbreaks by directly removing malicious code from infected computers, without the knowledge or authorization of those computers’ owners.

“We have gotten more comfortable, as a government, taking that step,” Adam Hickey, a deputy assistant attorney general for national security, said in an interview at the RSA cybersecurity conference in San Francisco.

The latest example of this approach came in April, when U.S. authorities wiped malware off of hacked servers used to control a Russian intelligence agency’s botnet, preventing the botnet’s operators from sending instructions to the thousands of devices they had infected. A year earlier, the Justice Department used an even more expansive version of the same technique to send commands to hundreds of computers across the country that were running Microsoft’s Exchange email software, removing malware planted by Chinese government agents and other hackers.

In both cases, federal prosecutors obtained court orders allowing them to access the infected devices and execute code that erased the malware. In their applications for these orders, prosecutors noted that government warnings to affected users had failed to fix the problems, thus necessitating more direct intervention.