Telkom has urged customers to patch and secure their Windows systems in the wake of the WannaCry ransomware which infected PCs around the world.
WannaCry caused a surge in traffic on the Telkom network, which the company said resulted in the degradation of performance of its service platforms.
Mobile subscribers complained on 16 May that they could not access Telkom’s USSD menu and that the mobile app was not working.
The outage made it impossible for Telkom subscribers to buy data bundles or manage their accounts.
It was also not possible to get through to Telkom’s call centre, and its website went down intermittently.
WannaCry is inert, but watch out
A security researcher stopped WannaCry in its tracks by inadvertently activating its kill switch, but Telkom warned that devices still remain vulnerable to the underlying attack.
Called EternalBlue, the attack was leaked online by hacking group The Shadow Brokers, who breached the NSA and stole a cache of cyber weapons belonging to the US government.
The NSA alerted Microsoft to the breach and the nature of the vulnerability it had discovered in Windows. By March, Microsoft had issued a patch.
However, many machines remain unpatched. A failure which the WannaCry creators exploited.
“Devices and systems remain vulnerable until they are patched,” said Telkom.
“Unpatched devices such as laptops, PCs, and tablets may continue to generate excessive network traffic and could be vulnerable to a potential second wave of the virus, should it appear in a different variant.”
Security researchers have warned of a recently-discovered attack which also uses exploits leaked by The Shadow Brokers.
Called EternalRocks, the attack uses seven of the leaked exploits – WannaCry only used two.
Windows users can check if their operating system is up to date by going to Settings > Update and Security > Windows Update.