Improve randomness of uploaded file names and files created by tempnam() #14364
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staabm
reviewed
May 29, 2024
arnaud-lb
changed the title
arnaud-lb
changed the title
TimWolla
approved these changes
May 30, 2024
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Uploaded files are created with a name in the form
/tmp/phpXXXXXX, whereXXXXXXis given one of 62^6 different values bymkstemp(3). According to this blogpost, it is possible to guess this name by brute forcing, with a reasonable number of attempts. This can be used to exploit a vulnerable applications.Here I add 64 bits of additional randomness before the
XXXXXXpattern, to make this attack unpractical.The change also applies to tempnam() and to platforms without
mkstemp().