The breach affects at least two internal drives, as well as emails, calendars and contacts of many staff members.
CBC News spoke to multiple sources with knowledge of the situation, including employees who have received instructions on how the breach affects their ability to work.
Some were told to stop working remotely as of last Wednesday.
CBC News has also seen three internal emails sent to Global Affairs staff.
Another email said the internal systems were vulnerable between December 20, 2023 and January 24, 2024.
It informed anyone who connected remotely using a SIGNET laptop that their information may be vulnerable.
The VPN system was managed by Shared Services Canada, the GAC notice said.
Shared Services Canada is a federal department created in 2011 to take over the delivery of email, data centres and network services for many government departments and agencies.
The statement also said connectivity in GAC buildings is fully functioning and that employees working remotely in Canada have been provided with workarounds.
No word yet on scope of data breach According to Global Affairs, SIGNET is the department's secure computer network.
One part of the network holds personal information on shared drives, including employees' personal information.
It's not clear whether secret information was lost in the breach, which lasted longer than a month.
Shared Services Canada and the Canadian Centre for Cyber Security - which is part of the Communications Security Establishment, Canada's cyber-security organization - are investigating the breach, GAC's email to staff said.
Although sensitive diplomatic cables are sent using an encrypted system, a source told CBC News that some drafts of sensitive correspondence and some intelligence may have been stored in the affected drives.
In the interim, some Canada-based Global Affairs employees with security clearance are not able to work from home.
A senior diplomatic source told CBC News that on several occasions in the past year, staff were told to immediately change passwords or reboot software but were not given any further details.
This Cyber News was published on www.cbc.ca. Publication date: Wed, 31 Jan 2024 01:14:04 +0000