[UNIX] PBLang Information Disclosure, Privileges Escalation and Cross Site Scripting

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  PBLang Information Disclosure, Privileges Escalation and Cross Site 
Scripting
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SUMMARY

" <http://pblang.drmartinus.de/> PBLang is a powerful flatfile Bulletin 
Board System. It combines many features of a professional board, but does 
not even require SQL support. It is completely based on text-file."

PBLang  has been discovered to contain multiple vulnerabilities, these 
vulnerabilities allow a remote attacker to disclose sensitive information, 
to escalate his privileges and to cause cross side scripting.

DETAILS

Vulnerable Systems:
 * PBLang version 4.65 and prior

Information Disclosure Vulnerability:
sendpm.php contains a flaw that allows a registered user to view other 
users' password hashes, as well as their PM's and other files in the forum 
(and outside of the forum directory too).

Exploit:
By using the following URL:
http://example.com/pblang/sendpm.php?to=[username]&subj=[doesnt 
matter]&num=1&orig=/home/public_html/pblang/db/members/[username]

It will load [username]'s entire account information including the MD5'ed 
password hash and maybe hidden email information. It will be shown in web 
page's source code, not in the page itself, so right click and view page 
source. This method allows accessing any file in the system using web 
server's privileges, including /etc/passwd.

Privilege Escalation Vulnerability:
Flaws in delpm.php allow any registered user to delete anyone else's PM's 
as long as their logged in (doesn't need to be privileged). This could 
allow unprivileged users to harass other users.

Exploit:
The following URL can be used to test your system for the mentioned 
vulnerability:
http://localhost/pblang/delpm.php?id=[PMID]&a=[Target user name]

Cross Side Scripting:
The module pmpshow.php shows the PMs a user has received, however, the 
body of the received PM is not checked for any harmful characters like < > 
and ".

Exploit:
Type in the body of the PM your going to send a victim.
"<script language="javascript">alert("XSS");</script>"

An alert box saying "XSS" should pop up.

In addition, the modules pm.php and search.php are also vulnerable to 
cross side scripting.


ADDITIONAL INFORMATION

The information has been provided by  <mailto:[email protected]> 
Raven.



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