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.
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:
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.
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