iPlanet Web Server Log Analyzer Input Filtering Flaw Lets Remote Users Conduct Cross-Site Scripting Attacks Against Administrators
SecurityTracker Alert ID: 1008208|
SecurityTracker URL: http://securitytracker.com/id/1008208
(Links to External Site)
Date: Nov 17 2003
Disclosure of authentication information, Disclosure of user information, Execution of arbitrary code via network, Modification of user information|
Exploit Included: Yes |
Version(s): 6.0 Service Pack 5 and prior; 4.1 Service Pack 12 and prior|
An input validation vulnerability was reported in the iPlanet Web Server in the Log Analyzer. A remote user can cause arbitrary scripting code to be executed by a target administrator when the target administrator views a log file.|
In March 2003, Infohacking Research reported that a remote user can set a malicious hostname containing HTML scripting code in the domain name system (DNS) and then make an HTTP request to a target server. If the target iPlanet Web Server is configured to perform inverse hostname lookups, the user-supplied HTML scripting code may be recorded in the web server log file.
When a target administrator runs the Log Analyzer to view the affected log entry, arbitrary scripting code will be executed by the target administrator's browser. The code will originate from the Log Analyzer application and will run in the security context of that application. As a result, the code will be able to access the target administrator's cookies (including authentication cookies), if any, associated with the security zone that the application runs in, access data recently submitted by the target administrator via web form to the application, or take actions on the application acting as the target administrator.
Some demonstration exploit hostnames are provided:
<script>alert( a )</script>
<script>alert( a )</script>.infohacking.com
<script>alert( a )</script>.infohacking.com
Some images showing the effects of a demonstration exploit is available at:
A remote user can access the target administrator's cookies (including authentication cookies), if any, associated with the security zone that the iPlanet administrative interface runs in, access data recently submitted by the target administrator via web form to the application, or take actions on the application acting as the target administrator.|
No solution was available at the time of the original report.|
Vendor URL: www.sun.com/ (Links to External Site)
Input validation error|
|Underlying OS: Linux (Red Hat Linux), Linux (Sun), UNIX (AIX), UNIX (HP/UX), UNIX (Solaris - SunOS), Windows (NT), Windows (2000)|
This archive entry has one or more follow-up message(s) listed below.|
Source Message Contents
Subject: Log corruption on multiple webservers, log analyzers,...|
something that could be interesting...
We have decided not to contact any vendor (many vendors are vulnerable and
we have not enough time...sorry) and made this advisory public in this
ILLC - Inverse Lookup Log Corruption
Corruption) that allows us to corrupt the logs generated by many web
servers that are doing inverse address resolution.
Impact of this technique:
- Code execution (XSS) on boxes that are running log analyzers (web
servers that have buit-in report analisys tools,etc.)
On some specific scenarios, we have been able to hide the entire http
request to the log viewer.
Most of the actions were possible because of the lack of filtering when
parsing host names between different applications.
1. A "name" (Net, Host, Gateway, or Domain name) is a text string up
to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus sign (-
), and period (.). Note that periods are only allowed when they serve to
delimit components of "domain style names". (See RFC-921, "Domain Name
System Implementation Schedule", for background). No blank or space
characters are permitted as part of a name. No distinction is made between
upper and lower case. The first character must be an alpha character. The
last character must not be a minus sign or period.... Single character
names or nicknames are not allowed....
3.5. Preferred name syntax
... The labels must follow the rules for ARPANET host names. They must
start with a letter, end with a letter or digit, and have as interior
characters only letters, digits, and hyphen. There are also some
2.1 Host Names and Numbers
The syntax of a legal Internet host name was specified in RFC-952 [DNS:4].
One aspect of host name syntax is hereby changed: the restriction on the
first character is relaxed to allow either a letter or a digit. Host
software MUST support this more liberal the RFCs. Note that under BIND 8,
you may need to add "check-names master ignore" to the zone definition
11. Name syntax
Occasionally it is assumed that the Domain Name System serves only the
purpose of mapping Internet host names to data, and mapping Internet
addresses to host names. This is not correct, the DNS is a general (if
somewhat limited) hierarchical database, and can store almost any kind of
data, for almost any purpose.
The DNS itself places only one restriction on the particular labels that
can be used to identify resource records. That one restriction relates to
the length of the label and the full name. The length of any one label is
limited to between 1 and 63 octets. A full domain name is limited to 255
Independently of what should be the legal host name syntax, it seems that
operating systems allows host names with arbitrary characters.
server/log analyzer,etc., will be doing inverse address resolution and
that the attacker could control in any way the responses to those inverse
Examples of attacks:
(exploited succesfully on Apache 2.0.44 on Windows/Linux, and Iplanet 6
Scenario: a machine with a host name as "22.214.171.124" makes a request
to an Apache server. If the server dosn`t generate any error, on the
access log you will see an access request from a client
called "126.96.36.199", what apparently seems to be a valid request from
a client that server was unable to resolve to a host name. So the real IP
wouldn't appear in the access log file.
188.8.131.52 - - [28/Feb/2003:10:39:01 +0100] "GET / HTTP/1.1" 200
1786 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
184.108.40.206 - - [28/Feb/2003:10:39:46 +0100] "GET /badrequest.html
HTTP/1.1" 404 294 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
If the request produces some error, you will see an entry in the error log
file were you could see the real IP, although the web server has the
inverse lookup activated.
[Fri Feb 28 10:39:46 2003] [error] [client 172.26.50.45] File does not
exist: C:/Archivos de programa/Apache Group/Apache2/htdocs/badrequest.html
in a complete anonymous http access for a client in a usual web surfing
activity, that is, if there are not broken links,etc.
preview (see link below):
(Succesfully exploited on Apache 2.0.44 on Windows/Linux, on IIS 6.0 and
Iplanet 6 on Windows)
When generating a report, with some log analyzers (that show results in
html), the script will be executed.
*Note: in IIS 6.0 case we needed to restrict access on webserver by domain
name in order to force inverse lookup resolution.
*Note2: in the Iplanet case we needed to simulate a FQDN client host name
You can also set a host name were the script is only part of the entire
so when html formatted it will appear as a valid domain name:
Some log analyzers proved to be vulnerable to "ILLC":
WebTrends (see link below):
SurfStats (see link below):
WebLogExpert (see link below):
Iplanet comes with a buil-in tool to generate html reports based on access
and error logs. This tool is part of the administration web interface.
Moreover, Iplanet log analyzer always uses a web broser to show the
will be always exploitable.
Iplanet Log Analyzer (HTML report, see link below):
on some characters (for example <>).
-HIDING REQUESTS (Iplanet 6 on Windows)
In the specific case of Iplanet 6, we coul realise that there`s a way to
are visible in the access and error log files, but they would
made requests from a box with this host name:
the access log:
format=%Ses->client.ip% - %Req->vars.auth-user% [%SYSDATE%] "%Req-
>reqpb.clf-request%" %Req->srvhdrs.clf-status% %Req->srvhdrs.content-
length% "%Req->headers.referer%" "%Req->headers.user-agent%" %Req-
>reqpb.method% %Req->reqpb.uri% %Req->reqpb.query% "%Req->reqpb.protocol%"
format=.winmat.com - - [28/Feb/2003:10:22:25 +0100] "GET /evilrequest.html
HTTP/1.1" 404 292 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)"
GET /evilrequest.html - "HTTP/1.1" https-script.winmat.com
We suppose that server is processing the first part of the host name
and the rest of the string is not recognized as valid format, so nothing
Combining the possibility of hiding a request and the Cross Site Scripting
technique we could execute scripts on the machine that runs the Report
establishing a host name like this:
(See link below):
Many more evil actions can be done... it only depends on the attacker's
IDSs, etc. We think that probably this technique could be used in the same
way in other scenarios.
Exploiting http headers for log corruption
Controlling inverse lookup responses is not always possible for the
attacker. We tried to figure out another, more generic attack to corrupt
The first that came to us was to use faked http headers in order to
achieve the same result: execution of scripts by log analyzers.
There are a lot of http headers that can be used to inject code in a log
file. We are not going to discuss all of them in this paper, but only to
outline some generic ways to do it.
The main objective here is to choose the right header to inject code in
web logs, but probably it will be filtered by many application firewalls
usually is not being checked for suspicious secuence of characters, and
An example on how to trick a log analizer to execute a script we
the web server log. Some log analyzers reading this logs and generating
HTML formatted reports without filtering the output, will execute the
-Examples of vulnerables log analyzers-
WebExpert (see link below):
LoganPro (see link below):
To solve this kind of problems it would be nice a more aggressive
filtering on DNS responses and HTTP requests on all the headers.
To finish this short analisys we would like to make some questions:
Are log analyzers thrusting too mutch on log files?
Maybe, are web servers the ones that would have to filter what they write
Is the operating system the one that have to filter the returned values
from DNS servers?
Are the actual legal domain name hosts allowed too mutch liberal?
Sorry for our bad english.
letting us doing this "research".
Infohacking Research 2001-2003
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