Ashkan Soltani, an independent privacy and security researcher, said such a move would give attackers "a toehold" in Twitter's internal network, potentially allowing them either to sniff out user information as it traveled across the company's system or break into specific areas, such as the authentication servers that process users' passwords.
In a telephone interview Friday, Soltani said that the relatively limited number of users affected suggested either that attackers weren't on the network long or that they were only able to compromise a subset of the company's servers.
Twitter is generally used to broadcast messages to the public, so the hacking might not immediately have yielded any important secrets. But the stolen credentials could be used to eavesdrop on private messages or track which Internet address a user is posting from.
