AdBlock Plus author calls out Firefox over nine-year-old master password bug

While a growing number of people are turning to dedicated password manager solutions such as LastPass, 1Password, and Dashlane, some still opt to use the built-in functionality provided by their web browsers. Of course, there is a matter of trust involved when using any such service or software to store your sensitive credentials as well as how swift a vendor's response ends up being if a critical flaw is discovered.

Unfortunately for Mozilla, it appears that its Firefox browser has for nine years only executed a single iteration of SHA-1 in order to hash the master password with a random salt in order to produce an encryption key for the password database. According to some analysis by Wladimir Palant, author of AdBlock Plus, "at least 100,000 iterations" would be far more effective in diminishing the effectiveness of brute force attacks. To lend further context, Palant also offered up some calculations:

"The problem here is: GPUs are extremely good at calculating SHA-1 hashes. Judging by the numbers from this article, a single Nvidia GTX 1080 graphics card can calculate 8.5 billion SHA-1 hashes per second. That means testing 8.5 billion password guesses per second. This article estimates that the average password is merely 40 bits strong, and that estimate is already higher than some of the others. In order to guess a 40 bit password you will need to test 239 guesses on average. If you do the math, cracking a password will take merely a minute on average then."

Of course, it is worth noting that the Microsoft article cited by Palant is over 11 years old, so whether or not the average password remains at 40 bits (which is the equivalent of a five character ASCII text string) may well be up for debate. When queried about his provocative suggestion that people "do not bother" using a master password in Firefox, he qualified his remark and said:

"Whether you have a four characters master password or a ten characters one doesn’t matter much – the latter is an inconvenience to you but usually doesn’t improve security considerably."

At present, users have no control over the number of SHA-1 rounds applied to the master password and salt, however, Robert Relyea in the thread has suggested updating Firefox to use "10000 (10K) in debug builds and 1000000 (1M) in optimized builds." Aside from leveraging Mozilla's experimental, standalone password manager, Lockbox, which relies on a Mozilla Account, the company has yet to provide a response and solution to the issue. In the meantime, users may need to consider their password management arrangements in light of the situation.

Source: Wladimir Palant via Bleeping Computer

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