Salt Typhoon exploits critical Cisco flaw to breach Canadian network

Canadian and US authorities have attributed a cyberattack on a Canadian telecommunications provider to state-sponsored actors allegedly linked to China. The attack exploited a critical vulnerability that had been patched 16 months earlier.

According to a statement issued on Monday by Canada’s Communications Security Establishment (CSE), the breach is attributed to a threat group known as Salt Typhoon, believed to be operating on behalf of the Chinese government.

‘The Cyber Centre is aware of malicious cyber activities currently targeting Canadian telecommunications companies,’ the CSE stated, adding that Salt Typhoon was ‘almost certainly’ responsible. The US FBI released a similar advisory.

Salt Typhoon is one of several threat actors associated with the People’s Republic of China (PRC), with a history of conducting cyber operations against telecommunications and infrastructure targets globally.

In late 2023, security researchers disclosed that over 10,000 Cisco devices had been compromised by exploiting CVE-2023-20198—a vulnerability rated 10/10 in severity.

The exploit targeted Cisco devices running iOS XE software with HTTP or HTTPS services enabled. Despite Cisco releasing a patch in October 2023, the vulnerability remained unaddressed in some systems.

In mid-February 2025, three network devices operated by an unnamed Canadian telecom company were compromised, with attackers retrieving configuration files and modifying at least one to create a GRE tunnel—allowing network traffic to be captured.

Cisco has also linked Salt Typhoon to a broader campaign using multiple patched vulnerabilities, including CVE-2018-0171, CVE-2023-20273, and CVE-2024-20399.

The Cyber Centre noted that the compromise could allow unauthorised access to internal network data or serve as a foothold to breach additional targets. Officials also stated that some activity may have been limited to reconnaissance.

While neither agency commented on why the affected devices had not been updated, the prolonged delay in patching such a high-severity flaw highlights ongoing challenges in maintaining basic cyber hygiene.

The authorities in Canada warned that similar espionage operations are likely to continue targeting the telecom sector and associated clients over the next two years.

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