On Wednesday, the department published a proposal in the Federal Register and opened a two-month comment period.
The changes are proposed to the Wassenaar Arrangement, an international agreement reached in 1995, aimed at limiting the spread of "dual use" technologies that could be used for harm.
Forty-one countries participate in the Wassenaar Arrangement, and lists of controlled items are revised annually.
The Commerce Department's Bureau of Industry and Security (BIS) is proposing requiring a license in order to export certain cybersecurity tools used for penetrating systems and analyzing network communications.
If asked by the BIS, those applying for a license "must include a copy of the sections of source code and other software (e.g., libraries and header files) that implement or invoke the controlled cybersecurity functionality."
Items destined for export to government users in Australia, Canada, New Zealand or the U.K. -- the so-called "Five Eyes" nations which the U.S. belongs to -- would be subject to looser restrictions. Those nations' intelligence agencies collaborate closely.
The proposal would modify rules added to the Wassenaar Arrangement in 2013 that limit the export of technologies related to intrusion and traffic inspection.
The definition of intrusion software would also encompass "proprietary research on the vulnerabilities and exploitation of computers and network-capable devices," the proposal said.
Tools that would not be considered intrusion software include hypervisors, debuggers and ones used for reverse engineering software.
There has long been concern that software tools in the wrong hands could cause harm. But security professionals who conduct security tests of organizations often employ the same software tools as those used by attackers.
Thomas Rid, a professor in the Department of War Studies at King's College London, wrote on Twitter that the proposed export regulations "seem too broad; could even damage cybersecurity."
Many private computer security companies sell information on software vulnerabilities for commercial purposes, a practice that has been criticized.
Those companies have defended their sales models, arguing that without a financial incentive, the software vulnerabilities may not have been found, which ultimately protects users. Many have policies that forbid selling sensitive information to unvetted parties.
The proposal said there is a "policy of presumptive denial for items that have or support rootkit or zero-day exploit capabilities."
Rootkits are hard-to-detect programs used for electronically spying on a computer, and a zero-day exploit is attack code that can take advantage of a software flaw.
Changes to the list of controlled items covered by the Wassenaar Agreement are decided by consensus at its annual plenary meeting in December.
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