Kaspersky Password Manager 的漏洞

Hacker News Daily 上看到「Kaspersky Password Manager: All your passwords are belong to us」這篇,講 Kaspersky Password Manager (KPM) 嚴重的安全漏洞,另外在 Hacker News 上的討論「Kaspersky Password Manager: All your passwords are belong to us (ledger.com)」也有提到一些有趣的東西。

標題的 All your passwords are belong to us 是出自「All your base are belong to us」這個梗的變形。

這包安全問題主要的原因是因為 KPM 沒有使用 CSPRNG,而且也沒有正確 seed,所以極為容易被猜出密碼本身。

KPM 的 Web 版使用了 Math.random(),在各家瀏覽器主要是用 xorshift128+ 實做 Math.random(),作者沒有針對這塊再花時間研究,但很明顯的 Math.random() 不是個 CSPRNG:

The underlying PRNG used by Chrome, Firefox and Safari for Math.random() is xorshift128+. It is very fast, but not suitable to generate cryptographic material. The security consequences in KPM has not been studied, but we advised Kaspersky to replace it with window.crypto.getRandomValues(), as recommended by the Mozilla documentation page previously mentioned.

Note: Math.random() does not provide cryptographically secure random numbers. Do not use them for anything related to security. Use the Web Crypto API instead, and more precisely the window.crypto.getRandomValues() method.

而桌機版則是用了 MT19937,理論上取得 624 bytes 的輸出後就可以重建整個 PRNG 的內部狀態 (於是就可以預測後續的 output),但這代表你要知道其他網站的密碼,這點其實有點困難。

但作者發現 KPM 在產生 MT19937 的 seed 只跟時間有關,超級容易被預測:

So the seed used to generate every password is the current system time, in seconds. It means every instance of Kaspersky Password Manager in the world will generate the exact same password at a given second.

於是可以直接暴力解出所有的可能性:

The consequences are obviously bad: every password could be bruteforced. For example, there are 315619200 seconds between 2010 and 2021, so KPM could generate at most 315619200 passwords for a given charset. Bruteforcing them takes a few minutes.

Hacker News 上有不少陰謀論的討論,像是:

Getting some DUAL_EC prng vibes.

Insert Kaspersky owned by Russia intelligence conspiracy here...

另外 Kaspersky 跟俄羅斯軍方的關係也是很知名,這些東西大概要到十來年後才會知道...

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