Cdric Clerget has discovered two vulnerabilities in PHP, which can be exploited by malicious people to bypass certain security restrictions.

1) The PHP "mb_send_mail()" function allows additional parameters to be passed to sendmail via the "additional_parameter" parameter. This can be exploited to cause sendmail to read arbitrary files on the system as configuration file and saving the resulting log file to arbitrary writable directories. The saved log file may contain portions of the file that was read as configuration file.

Example:
$additional_param = "-C ".$file_to_read." -X ".getcwd()."/".$output_file;
mb_send_mail($email_address, NULL, NULL, NULL, $additional_param);

Successful exploitation allows the bypassing of certain "safe_mode" and "open_basedir" restrictions.

The vulnerability has been confirmed in version 5.1.2 and also reported in version 4.x. Other versions may also be affected.

2) The PHP imap functions e.g. "imap_open()", "imap_body()", and "imap_list()" can be exploited to read arbitrary files and obtain listings of arbitrary directories even when "safe_mode" and "open_basedir" are configured. It is reportedly also possible to create, delete, and rename files with apache privileges using the "imap_createmailbox()", "imap_deletemailbox()", and "imap_renamemailbox()" functions.

Successful exploitation allows bypassing of certain "safe_mode" and "open_basedir" restrictions.

The vulnerability has been confirmed in PHP version 4.4.2 compiled with c_client 2004g. Other versions may also be affected.

Solution
Do not compile PHP to enable support of the mbstring or imap functions if they are not required.

Provided and/or discovered by
Cdric Clerget

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