Traffic got rerouted Monday through ISPs in countries known for internet surveillance.
Google suffered a brief outage and slowdown on Monday, with some of its traffic being rerouted through networks in Russia, China and Nigeria.
Incorrect routing instructions sent some of the search giant's traffic to Russian network operator TransTelekom, China Telecom and Nigerian provider MainOne between 1:00 p.m. and 2:23 p.m. PT, according to ThousandEyes, an internet research group.
"This incident at a minimum caused a massive denial of service to G Suite and Google Search," Ameet Naik, ThousandEyes' technical marketing manager, wrote in a blog post. "However, this also put valuable Google traffic in the hands of ISPs in countries with a long history of Internet surveillance.
MainOne seems to have been at the heart of the problem, according to an Ars Technica report. The Lagos-based provider apparently conducted an update that incorrectly declared its that system was the proper path for millions of Google IP addresses.
The problematic update caused a chain reaction in which China Telecom and Russia's TransTelekom to improperly accepted the route
Nigeria's MainOne said Tuesday the outage was caused by "an error during a planned network upgrade."
"The error was corrected within 74mins & processes put in place to avoid reoccurrence," MainOne tweeted.
Google said the cause was incorrect IP address routing, but noted it had been resolved. The search giant said it would conduct an internal investigation.
"The root cause of the issue was external to Google," a spokesperson said in an email statement. "There was no compromise of Google services."
Applications such as Gmail and Google Drive don't appear to have been affected, but 9to5Google reported that YouTube users experienced some slowdown.
Google doesn't consider the incident was malicious, the company told The Wall Street Journal.
Facebook also suffered a 40-minute outage on Monday, but the social network attributed the interruption in service to "a routine test."
First published at 5:41 a.m. PT.
Update at 9:07 a.m. PT: Adds MainOne explanation.
Update at 10 a.m. PT: Explains MainOne's role.
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