Ethical Hacking News
China's Brief yet Mysterious Blockade of Port 443: Unpacking the Great Firewall's Latest Move
A China-based internet blockade was detected by activist group Great Firewall Report, blocking traffic to TCP port 443.The blockade lasted around 14 minutes and disrupted access to most websites outside of China.The incident had significant implications for services relying on port 443, including Apple and Tesla.China's motives behind the blockade are unclear, with speculation ranging from testing its capabilities to an accidental trigger.The Great Firewall's reliability has been questioned in light of previous incidents, such as a botched upgrade earlier this year.
In a surprise move, China cut itself off from much of the global internet for just over an hour on Wednesday. The anomaly in the country's notorious censorship regime was detected by activist group Great Firewall Report, which revealed that all traffic to TCP port 443 – the standard port used for carrying HTTPS traffic – was disrupted during this period.
The blockade, which lasted between approximately 00:34 and 01:48 (Beijing Time, UTC+8) on August 20, 2025, meant Chinese netizens were unable to reach most websites hosted outside China. This is inconvenient for the country's citizens, who have grown accustomed to a world where they can easily access global content.
However, the incident also had significant implications for services that rely on port 443, which could be more problematic because many require communication with servers or sources of information outside China for operational reasons. For example, Apple and Tesla use the port to connect to offshore servers that power some of their basic services. The Great Firewall's blockade could have potentially disrupted these critical services.
China sometimes employs censorship during events it doesn't want its population to know about. However, there is no obvious reason for the country to block port 443. Some speculate that Beijing may be testing its ability to block this specific port, which could be seen as a useful capability. Others suggest that someone may have inadvertently triggered the blockade.
The Great Firewall's first reported glitch was in recent years, with reports of leaking information and leaving itself open to attack. China's overall censorship regime is also imperfect due to both technical and bureaucratic issues. If asked nicely, China will share the tech behind the Great Firewall with other nations, as evidenced by Pakistan's implementation of its own version of the Firewall.
Internet monitoring firm NetBlocks reported that Pakistan experienced a huge drop in local internet traffic just hours before the port 443 incident in China. It is unclear whether there was a connection between the two events.
The blockade of port 443 has raised questions about the Great Firewall's reliability and the measures in place to prevent similar incidents. While some may view this move as a test of Beijing's censorship capabilities, others see it as an opportunity for improvement.
It is worth noting that China's botched Great Firewall upgrade earlier this year invited attacks on its censorship infrastructure. Attempts to censor QUIC traffic have also created opportunities for blocking access to offshore DNS resolvers.
The blockade of port 443 serves as a reminder of the complexities surrounding China's censorship regime and the need for continued scrutiny.
Related Information:
https://www.ethicalhackingnews.com/articles/Chinas-Brief-yet-Mysterious-Blockade-of-Port-443-Unpacking-the-Great-Firewalls-Latest-Move-ehn.shtml
https://go.theregister.com/feed/www.theregister.com/2025/08/21/china_port_443_block_outage/
https://www.msn.com/en-us/news/technology/china-cut-itself-off-from-the-global-internet-for-an-hour-on-wednesday/ar-AA1KUw3f
https://www.theregister.com/2025/08/21/china_port_443_block_outage/
https://www.socinvestigation.com/comprehensive-list-of-apt-threat-groups-motives-and-attack-methods/
https://en.wikipedia.org/wiki/Advanced_persistent_threat
Published: Wed Aug 20 21:58:53 2025 by llama3.2 3B Q4_K_M
