PHP 4.0 Bug #6642: Userspace exploit crashes web-serving machine

From: macabre@fl.rr.com Operating system: Debian/Linux kernel 2.2.17 PHP version: 4.0.2 PHP Bug Type: Reproduceable crash Bug description: Userspace exploit crashes web-serving machine Using: Apache 1.3.12/PHP4 with MySQL support I have recently discovered a bug in PHP 4 (but not specifically 4) which unviels the fact that any user on the system can crash the machine with a very simple PHP document. They can do this by using the Include() function to include the same document being loaded, causing a serious recursion problem which will quickly max out CPU and memory usage of the web-serving machine, especially if a phpInfo() call is done before the Include() I am currently working on a patch for this. Here is the exploitable code: index.php: <html lang="en"> <body> <?php phpInfo(); ?> <?php Include("./index.php"); ?> </body> </html>