LastPass officials warned Monday that attackers have compromised servers that run the company's password management service and made off with cryptographically protected passwords and other sensitive user data. It was the second breach notification regarding the service in the past four years.
In all, the unknown attackers obtained hashed user passwords, cryptographic salts, password reminders, and e-mail addresses, LastPass CEO Joe Siegrist wrote in a blog post. It emphasized that there was no evidence the attackers were able to open cryptographically locked user vaults where plain-text passwords are stored. That's because the master passwords that unlock those vaults were protected using an extremely slow hashing mechanism that requires large amounts of computing power to work.
"We are confident that our encryption measures are sufficient to protect the vast majority of users," Siegrist wrote. "LastPass strengthens the authentication hash with a random salt and 100,000 rounds of server-side PBKDF2-SHA256, in addition to the rounds performed client-side. This additional strengthening makes it difficult to attack the stolen hashes with any significant speed."
By contrast, many sites have used extremely fast hashing algorithms that provide minimal protection. Despite the rigor of the LastPass hashing regimen, the job of cracking a single hash belonging to a specific, targeted individual would be considerably less difficult and potentially within the ability of determined attackers, especially if the underlying password is weak. To prevent such attacks, LastPass officials are requiring all users who log in from new devices or IP addresses to first verify their account by e-mail unless they have multifactor authentication enabled. As an added precaution, LastPass is also prompting users to update their master passwords. LastPass users who haven't already done so should strongly consider enabling multifactor authentication.
The breach comes four years after LastPass officials detected anomalies in their server logs that were consistent with a network compromise. The data that may have been accessed in that 2011 event included hashed passwords, the underlying cryptographic salts, and user e-mail addresses. That same year, a security researcher reported finding a cross-site scripting (XSS) bug on the LastPass website that he said made it possible for attackers to steal sensitive user data. Information at risk, the researcher said, included e-mail addresses, password reminders, the list of sites users logged into, and the time, dates, and IP addresses of those logins. LastPass promptly fixed the bug.
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In all, the unknown attackers obtained hashed user passwords, cryptographic salts, password reminders, and e-mail addresses, LastPass CEO Joe Siegrist wrote in a blog post. It emphasized that there was no evidence the attackers were able to open cryptographically locked user vaults where plain-text passwords are stored. That's because the master passwords that unlock those vaults were protected using an extremely slow hashing mechanism that requires large amounts of computing power to work.
"We are confident that our encryption measures are sufficient to protect the vast majority of users," Siegrist wrote. "LastPass strengthens the authentication hash with a random salt and 100,000 rounds of server-side PBKDF2-SHA256, in addition to the rounds performed client-side. This additional strengthening makes it difficult to attack the stolen hashes with any significant speed."
By contrast, many sites have used extremely fast hashing algorithms that provide minimal protection. Despite the rigor of the LastPass hashing regimen, the job of cracking a single hash belonging to a specific, targeted individual would be considerably less difficult and potentially within the ability of determined attackers, especially if the underlying password is weak. To prevent such attacks, LastPass officials are requiring all users who log in from new devices or IP addresses to first verify their account by e-mail unless they have multifactor authentication enabled. As an added precaution, LastPass is also prompting users to update their master passwords. LastPass users who haven't already done so should strongly consider enabling multifactor authentication.
The breach comes four years after LastPass officials detected anomalies in their server logs that were consistent with a network compromise. The data that may have been accessed in that 2011 event included hashed passwords, the underlying cryptographic salts, and user e-mail addresses. That same year, a security researcher reported finding a cross-site scripting (XSS) bug on the LastPass website that he said made it possible for attackers to steal sensitive user data. Information at risk, the researcher said, included e-mail addresses, password reminders, the list of sites users logged into, and the time, dates, and IP addresses of those logins. LastPass promptly fixed the bug.
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