oss-security - PHP and some == wonkiness

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Message-ID: <55479C75.3070000@redhat.com>
Date: Mon, 04 May 2015 10:21:09 -0600
From: Kurt Seifried <kseifried@...hat.com>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: PHP and some == wonkiness

https://news.ycombinator.com/item?id=9484757 read the entire thread for
an ongoing series of "what the heck?".

Some examples include:
=================
This is well-known PHP-trick. Use === to right result.
  php > var_dump(md5('240610708') == md5('QNKCDZO'));
  bool(true)
  php > var_dump(md5('240610708'),   md5('QNKCDZO'));


  string(32) "0e462097431906509019562988736854"
  string(32) "0e830400451993494058024219903391"
  php > var_dump(md5('240610708') ===   md5('QNKCDZO'));


  bool(false)
  php > var_dump("0e462097431906509019562988736854" ==
"0e830400451993494058024219903391");
  bool(true)
  php > var_dump("0e462097431906509019562988736854" ===
"0e830400451993494058024219903391");
  bool(false)
  php > var_dump(md5('240610708') ===   md5('QNKCDZO'));


  bool(false)
  php > var_dump(md5('240610708') ==   md5('QNKCDZO'));

  bool(true)
  php > var_dump(md5('240610708') === md5('QNKCDZO'));
  bool(false)
=================

I'm guessing there is more than a bit of code that uses == to compare
passwords/etc. Something to be aware of.


-- 
Kurt Seifried -- Red Hat -- Product Security -- Cloud
PGP A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993


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