File System Security Issue in Custom Auth Article (finished) #6234
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I hope to address this security concern: If `$token->nonce` is set to [ANY USER INPUT] and later we run `file_put_contents($token->nonce, time())` are we allowing hackers to destroy any www-writable file in the system?
I did notice that `$nonce` is run through `base64_decode($nonce)` later in the article, implying nonce needs to be a Base64 string. Could this Regex be updated to only accept a Base64 string `[a-zA-Z+/]+={0,2}` for the nonce?
At the same time, Base64 allows `/` characters, so `file_put_contents()` would fail in those cases, so even this change, while secure, seems flawed. Replace [+/] with [-_]?
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Thank you @mattjanssen. |
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…ed) (mattjanssen, WouterJ) This PR was merged into the 2.3 branch. Discussion ---------- File System Security Issue in Custom Auth Article (finished) Finishes #5846 Original description: > | Q | A > | ------------- | --- > | Doc fix? | yes > | New docs? | no > | Applies to | all > | Fixed tickets | #5845 > > I hope to address this security concern: If `$token->nonce` is set to [ANY USER INPUT] and later we run `file_put_contents($token->nonce, time())` are we allowing hackers to destroy any www-writable file in the system? > > I did notice that `$nonce` is run through `base64_decode($nonce)` later in the article, implying nonce needs to be a Base64 string. Could this Regex be updated to only accept a Base64 string `[a-zA-Z+/]+={0,2}` for the nonce? > > At the same time, Base64 allows `/` characters, so `file_put_contents()` would fail in those cases, so even this change, while secure, seems flawed. Replace [+/] with [-_]? Commits ------- 673fd71 Hash nonce when using as file name 5f125f3 File System Security Issue in Custom Auth Article
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Finishes #5846
Original description: