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<h1 class="m-title">[KIS-2021-05] Concrete5 <= 8.5.5 (Logging Settings) Phar Deserialization Vulnerability</h1>
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<em>From</em>: Egidio Romano <research () karmainsecurity com>
<em>Date</em>: Mon, 19 Jul 2021 20:49:35 +0200
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<pre style="margin: 0em;">------------------------------------------------------------------------
Concrete5 <= 8.5.5 (Logging Settings) Phar Deserialization Vulnerability
------------------------------------------------------------------------
[-] Software Link:
<a rel="nofollow" href="https://www.concrete5.org">https://www.concrete5.org</a>
[-] Affected Versions:
Version 8.5.5 and prior versions.
[-] Vulnerability Description:
</pre><tt>The vulnerable code is located within the
</tt><tt>/concrete/controllers/single_page/dashboard/system/environment/logging.php
</tt><tt>script. Specifically, into the Logging::update_logging() method:
</tt><pre style="margin: 0em;">
61. public function update_logging()
62. {
63. $config = $this->app->make('config');
64. $request = $this->request;
65.
66. if (!$this->token->validate('update_logging')) {
</pre><tt>67. return
</tt><tt>$this->showError($this->token->getErrorMessage());
</tt><pre style="margin: 0em;">68. }
69.
70. // Load in variables from the request
</pre><tt>71. $mode = (string) $request->request->get('logging_mode') ===
</tt><tt>'advanced' ? 'advanced' : 'simple';
</tt><tt>72. $handler = $mode === 'simple' ? (string)
</tt><tt>$request->request->get('handler', 'database') : null;
</tt><tt>73. $logFile = $handler === 'file' ? (string)
</tt><tt>$request->request->get('logFile') : null;
</tt><tt>74. $enableDashboardReport =
</tt><tt>$request->request->get('enable_dashboard_report') ? true : false;
</tt><tt>75. $loggingLevel = strtoupper((string)
</tt><tt>$request->request->get('logging_level'));
</tt><tt>76. $intLogErrorsPost =
</tt><tt>$request->request->get('ENABLE_LOG_ERRORS') === 1 ? 1 : 0;
</tt><tt>77. $intLogEmailsPost =
</tt><tt>$request->request->get('ENABLE_LOG_EMAILS') === 1 ? 1 : 0;
</tt><tt>78. $intLogApiPost = $request->request->get('ENABLE_LOG_API')
</tt><tt>=== 1 ? 1 : 0;
</tt><pre style="margin: 0em;">79.
80.
81. // Handle 'file' based logging
82. if ($handler === 'file') {
83. $directory = dirname($logFile);
84.
85. // Validate the file name
86. if (pathinfo($logFile, PATHINFO_EXTENSION) !== 'log') {
</pre><tt>87. return $this->showError(t('The filename provided
</tt><tt>must be a valid filename and end with .log'));
</tt><pre style="margin: 0em;">88. }
89.
90. // Validate the file path, create the log file if needed
91. if (!file_exists($logFile)) {
</pre><tt>User input passed through the "logFile" request parameter is not
</tt><tt>properly sanitized before being used in a call to the file_exists()
</tt><tt>function at line 91. This can be exploited by malicious users to inject
</tt><tt>arbitrary PHP objects into the application scope (PHP Object Injection
</tt><tt>via phar:// stream wrapper), allowing them to carry out a variety of
</tt><tt>attacks, such as executing arbitrary PHP code. Successful exploitation
</tt><tt>of this vulnerability requires an administrator account.
</tt><pre style="margin: 0em;">
[-] Solution:
No official solution is currently available.
[-] Disclosure Timeline:
[20/12/2020] - Vendor notified through HackerOne
</pre><tt>[22/12/2020] - Vendor asks suggestions to fix the issue, feedback
</tt><tt>provided
</tt><pre style="margin: 0em;">[18/03/2021] - Version 8.5.5 released, vulnerability not fixed
[02/06/2021] - Asked for an update, no response
[06/07/2021] - Asked for an update, no response
[16/07/2021] - CVE number assigned
[19/07/2021] - Public disclosure
[-] CVE Reference:
The Common Vulnerabilities and Exposures project (cve.mitre.org)
has assigned the name CVE-2021-36766 to this vulnerability.
[-] Credits:
Vulnerability discovered by Egidio Romano.
[-] Other References:
<a rel="nofollow" href="https://hackerone.com/reports/1063039">https://hackerone.com/reports/1063039</a>
[-] Original Advisory:
<a rel="nofollow" href="http://karmainsecurity.com/KIS-2021-05">http://karmainsecurity.com/KIS-2021-05</a>
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<h3 class="m-thread">Current thread:</h3>
<ul class="thread">
<li><strong>[KIS-2021-05] Concrete5 <= 8.5.5 (Logging Settings) Phar Deserialization Vulnerability</strong> <em>Egidio Romano (Jul 19)</em>
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