CVE-2017-17976

published 2018-01-26

CVE-2017-17976: In Utilities.php in Perfex CRM 1.9.7, Unrestricted file upload can lead to remote code execution.

Priority P2 72 critical 9.8 CVSS 3.0

AV N AC L PR N UI N S U C H I H A H

EXPLOIT

In Utilities.php in Perfex CRM 1.9.7, Unrestricted file upload can lead to remote code execution.

Affected

1 ranges

Vendor	Product	Version range	Fixed in
perfexcrm	perfex_crm	—	—

Detection & IOCs extracted from sources · hover to see the quote

path admin/utilities/elfinder_init↗

filename shell.php5↗

command cmd=mkfile&name=shell.php5&target=[dir]↗

command cmd=put&target=[folder]&encoding=UTF-8&content=demo↗

• → Detect GET requests to the elFinder init endpoint with cmd=mkfile and a .php5 filename, indicating an attempt to create a PHP webshell via the misconfigured elFinder plugin. ↗
• → Detect POST requests to admin/utilities/elfinder_init with cmd=put, which is used to write arbitrary content (e.g., PHP code) into the previously created .php5 file. ↗
• → Flag file uploads or file creation events with .php5 extension in the web root, as the attack bypasses upload restrictions by using the .php5 extension instead of .php. ↗
• → Monitor for the X-Requested-With: XMLHttpRequest header combined with requests to the elfinder_init path, as the exploit relies on AJAX-style requests to the elFinder API. ↗
• → Alert on Content-Type: application/x-www-form-urlencoded POST requests to elfinder_init containing cmd=put, used to write webshell content while bypassing MIME-type restrictions by prepending a text line. ↗

• · The vulnerability is rooted in a misconfigured elFinder plugin bundled with Perfex CRM 1.9.7. The elFinder endpoint is exposed at admin/utilities/elfinder_init without sufficient file-type restrictions, allowing .php5 files to be created and written to. ↗
• · The affected file is Utilities.php in Perfex CRM 1.9.7; the unrestricted file upload is only confirmed for this specific version. ↗

CVSS provenance

nvd v3.0 9.8 CRITICAL CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd v2.0 7.5 HIGH AV:N/AC:L/Au:N/C:P/I:P/A:P

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