Twitter Inc shares fell almost 7 percent after the company said it was investigating unusual traffic that it said might be from state-sponsored hackers.
In what appeared to be an unrelated issue, a security firm also said that hackers used the platform to try to steal user data.
Twitter said in a blog that it discovered suspicious traffic to a customer-support forum while investigating a security bug that exposed user data, including users’ phone country codes and details on locked accounts. It said the bug was fixed on November 16.
Twitter said it observed a large amount of traffic to the customer support site coming from individual internet IP addresses in China and Saudi Arabia.
“During our investigation, we noticed some unusual activity involving the affected customer support form API. Specifically, we observed a large number of inquiries coming from individual IP addresses located in China and Saudi Arabia,” Twitter said in a press release.
Wedbush analyst Michael Pachter blamed the share price tumble on concerns that news of a breach could hurt growth and user engagement.
“Clearly, a breach like this impairs user trust in the platform,” he said.
Separately, security software maker Trend Micro Inc said in a blog earlier on Monday that attackers sent out two tweets in October in a bid to steal data from previously infected machines.
The hackers hid instructions in tweeted memes that secretly ordered infected devices to send information, including user names, screen images and other content, Trend Micro said.
A Twitter spokesperson declined comment on the Trend Micro report. (AFP)
