Category Archives: Research

Articles/Whitepapers

Abusing Trackback utility

I was researching a bit into the wordpress trackback utility. This is how it works:
You submit a post with trackback urls, and when you publish the post, the wordpress sends out a request to the URL you mentioned in the trackback URLs. Essentially this happens in the background.

You—–> WordPress Server———->Trackback URL

The trackback request to the trackback URL is not made by your browser, but the request will be sent by your server hosting wordpress application. This was a bit surprising to me, as what if my wordpress hosting company does not allow outbound traffic? Anyways the request is nothing special , its a straight forward post request to the trackback URL with the following parameters.

title
url
blog_name
excerpt.

I wrote a simple perl script which you can use to send fake trackback request. Although the request will go from your IP address, (unless you use some anonymous proxy) You can specify the Fake Url and other parameters which will appear to the victim’s wordpress. The Only solution i can think to avoid getting fake trackbacks is by having a check on the submitted url to see if it resolves to the same ip address. However, that might create some other problems.

However, I would be more interested in knowing if we can abuse it still further. At the moment i cant think of any more attack vectors to exploit this. As the connection to the trackback URL is made by wordpress server, can we not make it connect to a malicious host. Can we not make it connect to different ports on different hosts… blah.. blah blah... I look forward to hearing comments on this. BTW this blog is not just about hacking wordpress:)

WordPress 2.1.2 xmlrpc Security Issues

WordPress 2.1.2 xmlrpc Multiple Vulnerabilities:

Affected Versions: These issues were reported in version 2.1.2,(current stable version) and its very likely that previous versions may also be vulnerable.

1. Privilidge Escalation:

Under normal circumstances (through web interface) a user in contributor role only has access to following functions:

a. read
b. edit_posts

functionality ‘publish_posts’ is restricted to users in the author, editor or administrator roles. However, this is not implemented in xmlrpc.php and this allows a user in the contributor roles to publish a previously saved post to the website.

No exploit code is required.

2. SQL Injection:

This is only exploitable by authenticated users.
The post_id parameter is not properly sanitized before passing its value to the backend database which results in a Sql injection. Exploiting this is pretty trivial. As, it is an integer based injection, it works irrespective of the setting “magic quote”. . I wrote a Simple Proof Of Concept for this.
Download Exploit
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Exploit
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Successful Exploitation of this will give you usernames and md5 hash of password of all users including admin user. Before you run mdcrack on this hash, read my previous post on wordpress cookies as this will save your time.
Once you have the admin user hash needless to say you can create a php backdoor and that essentialy is game over.

About Poc:
The poc demonstrates how critical SQL injection vulnerabilities can be. In this example,the poc goes beyond obtaining admin hashes. It also returns the username and encrypted password of the mysql user(s). If the database is running as privilidged user, this will also try to fetch the /etc/passwd file, or any other file for that matter. As this injection is in an integer field it works irrespective of the setting magic quote :-)

Workaround:
1. Disable xmlrpc if you dont use it or restrict its access to trusted users only.

Vendor’s response:
1. vendor notified on 22nd March 2007.
2. New Version released on 2nd April 2007.
3. Advisory released on 2nd April 2007

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SQL Injection Cheat Sheet

cheat sheet. Although there are so many articles on internet which talks about Sql Injection, this is the only document i know which is ‘complete’.

Abusing TCP/IP name resolution in Windows to carry out phishing attacks.

I was playing with name resolution in windows and i found that it sends broadcast requests over the network for the hostnames not resolved by DNS or WINS services. This is characteristic behaviour of windows and *nix boxes do not send any such broadcast requests. As these are the broadcast request, these can easily be abused to carry out phishing attacks. I wrote a small paper on this. You can access it here.

UPDATES: Here is good article from microsoft which discusses this process in detail. Here are a few drawbacks of this atatck:

1. This attack will ony work for domain names that are less than 16 characters.

2. Routers typically do not forward broadcasts, so only NetBIOS name on the local network can be resolved and the attacker thus has to be on the same local network.

3. The victim has to enable Netios Over TCP/IP to send out broadcast request.