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Vulnerability mirror (Perl) Affected mirror 2.9 Description Wise Cat found following. mirror is a Perl script which is widely used for making copy of remote FTP site. It's included in FreeBSD packages. There are security holes, which allows overwrite local files from remote ftp site with permissions of the user who uses mirror. Then retrieving directory listing mirror doesn't check filename or directory name to contain ".." or "\" This allows to create or overwrite files in directory different from destination. To simply test this bug you can create " .." directory on your ftp site and mirror your site. Mirror will create temporary files in directory one level higher then specifyed. This way you couldn't overwrite some useful information, but this may be used, for example, to fill out / directory (if mirror is ran from root). But with putting little changes into you ftpd (for example making him change '\' to '/' on listings) you can force mirror to overwrite _any_ file with permissions of mirror user then he mirrors your ftp site. This was tested with: $ mirror -v $Id: mirror.pl,v 2.9 1998/05/29 19:01:07 lmjm Exp lmjm $ Solution Upgrade. SuSE: ftp://ftp.suse.com/pub/suse/i386/update/5.3/n1/mirror-2.8.f4-89.i386.rpm ftp://ftp.suse.com/pub/suse/i386/update/6.1/n1/mirror-2.8.f4-89.i386.rpm ftp://ftp.suse.com/pub/suse/axp/update/6.1/n1/mirror-2.8.f4-89.alpha.rpm ftp://ftp.suse.com/pub/suse/i386/update/6.2/n1/mirror-2.8.f4-89.i386.rpm Debian GNU/Linux 2.1 could be remotely exploited. This has been fixed in mirror version 2.9-2.1. Anyhow. A simple fix to overcome this problem is to add the following to your mirror.defaults (and to any package that overrides this setting): name_mappings=s:\.\./:__/:g This should convert names like: " ../rot" to " __/rot" Quick patch to the mirror.pl script to warn/log about attempts follows: *** mirror.pl Mon Jun 8 11:55:27 1998 --- /usr/local/mirror2.9/mirror Wed Sep 29 16:34:01 1999 *************** *** 2657,2662 **** --- 2657,2701 ---- $no_rename = (! $remote_has_rename) || ($remote_fs eq 'macos' && ! $get_file); foreach $src_path ( @xfer_src ){ + + ## + #BEGIN jcp@EUnet.pt 1999/09/29 + # + #Date: Tue, 28 Sep 1999 18:27:54 +0400 + #From: 3APA3A <wise@tomcat.ru> + #To: BUGTRAQ@SECURITYFOCUS.COM + #Subject: mirror 2.9 hole + # + #Hello BUGTRAQ@SECURITYFOCUS.COM, + # + #mirror is a Perl script which is widely used for making copy of remote + #FTP site. It's included in FreeBSD packages. There are security holes, + #which allows overwrite local files from remote ftp site with + #permissions of the user who uses mirror. Then retrieving directory + #listing mirror doesn't check filename or directory name to contain + #".." or "\" This allows to create or overwrite files in directory + #different from destination. + # + #To simply test this bug you can create " .." directory on your ftp + #site and mirror your site. Mirror will create temporary files in + #directory one level higher then specifyed. This way you couldn't + #overwrite some useful information, but this may be used, for example, + #to fill out / directory (if mirror is ran from root). + # + #But with putting little changes into you ftpd (for example making him + #change '\' to '/' on listings) you can force mirror to overwrite _any_ + #file with permissions of mirror user then he mirrors your ftp site. + # + # + #Tested with: + #$ mirror -v + #$Id: mirror.pl,v 2.9 1998/05/29 19:01:07 lmjm Exp lmjm $ + + if( $src_path =~ /\w*\.\.\//){ + &msg( $log, "WARNING: BAD dir detected, skipping: $src_path\n" ); + next; + } + #END jcp@EUnet.pt if( $get_file ){ $srci = $remote_map{ $src_path }; }