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IPS Community Suite <= 4.5.4.2 (previewBlock) PHP Code Injection 
Vulnerability
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[-] Software Link:

https://invisioncommunity.com


[-] Affected Versions:

Version 4.5.4.2 and prior versions.


[-] Vulnerability Description:

The vulnerability exists because the 
IPS\cms\modules\front\pages\_builder::previewBlock() method allows to 
pass arbitrary content to the IPS\_Theme::runProcessFunction() method, 
which will be used in a call to the eval() PHP function. This can be 
exploited to inject and execute arbitrary PHP code. Successful 
exploitation of this vulnerability requires an account with permission 
to manage the sidebar (such as a Moderator or Administrator) and the 
"cms" application to be enabled.


[-] Proof of Concept:

https://[host]/[ips]/index.php?app=cms&module=pages&controller=builder&do=previewBlock&block_plugin=stats&block_template_use_how=copy&block_plugin_app=core&_sending=block_content&block_content=RCE%0ACONTENT;}}phpinfo();die;/*


[-] Solution:

Apply the vendor patch or upgrade to version 4.6.0 or later.


[-] Disclosure Timeline:

[02/02/2021] - Vendor notified through HackerOne
[02/04/2021] - Asked for an update
[06/04/2021] - Vendor replies they already released a targeted patch
[13/05/2021] - CVE number assigned
[28/05/2021] - Public disclosure


[-] CVE Reference:

The Common Vulnerabilities and Exposures project (cve.mitre.org)
has assigned the name CVE-2021-32924 to this vulnerability.


[-] Credits:

Vulnerability discovered by Egidio Romano.


[-] Other References:

https://hackerone.com/reports/1092574


[-] Original Advisory:

https://karmainsecurity.com/KIS-2021-04