Add mitigation against BREACH #18254
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| @@ -1057,7 +1057,7 @@ public static function getInstanceId() { | |||
| /** | |||
| * Register an get/post call. Important to prevent CSRF attacks. | |||
| * | |||
| * @return string Generated token. | |||
| * @return string XOR'd CSRF token with an appended random separated by `:` | |||
LukasReschke
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sigh |
| @@ -415,8 +421,25 @@ public function passesCSRFCheck() { | |||
| return false; | |||
| } | |||
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| if(is_null($this->crypto)) { | |||
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Fixed. Needed some small change to base.php though since autoloading is not available at this stuff and cyclic dependency fun…
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While BREACH requires the following three factors to be effectively exploitable we should add another mitigation: 1. Application must support HTTP compression 2. Response most reflect user-controlled input 3. Response should contain sensitive data Especially part 2 is with ownCloud not really given since user-input is usually only echoed if a CSRF token has been passed. To reduce the risk even further it is however sensible to encrypt the CSRF token with a shared secret. Since this will change on every request an attack such as BREACH is not feasible anymore against the CSRF token at least.
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A new inspection was created. |
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Let's try again before creating a new branch. |
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🚀 Test PASSed.🚀 |
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Reviews? 🙊 To test this basically take a look at the HTML source of ownCloud and check if the requesttoken is different each reload. Besides that click around and check if there are no CSRF token fails ;) |
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This wants reviewers lalalalalala – just 👍'ing is also fine 🙊 |
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looks good 👍 |
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Did some tests - works 👍 |
MorrisJobke
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Add mitigation against BREACH
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While BREACH requires the following three factors to be effectively exploitable we should add another mitigation:
Especially part 2 is with ownCloud not really given since user-input is usually only echoed if a CSRF token has been passed. (though there are parts such as the search box…)
To reduce the risk even further it is however sensible to encrypt the CSRF token with a shared secret. Since this will change on every request an attack such as BREACH is not feasible anymore against the CSRF token at least.
cc @owncloud/security-team Care to review?