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Fri, 24 Aug 2012

44Con Challenge

In a similar fashion to the BlackHat challenge held earlier this year, we're giving away a free ticket to our BlackOps course at this year's 44Con. As a penetration tester, knowledge of an issue is not enough when one needs to demonstrate risk to a client. Furthermore, when large numbers of potential targets are involved, it becomes crucial that effective attacks are packaged and automated to allow for mass-pwnage.

During an engagement, you notice that a fair portion of the client's SIP devices still have the default administrative password set. You're particularly interested in compromising these devices since they also have an embedded SSH service that can be activated and used to mask your actual position on the network.

The web-based administration console runs over HTTP (TCP/80) and the default administrative password is 123456. You also notice that a successful administrative login will result in a welcome message within the webpage title.

A HTTP login request to the SillySIP administrative console

Figure 1. A HTTP login request to the SillySIP administrative console

A (partial) response, from the SillySIP administrative console, for a successful login

Figure 2. A (partial) response, from the SillySIP administrative console, for a successful login

The Challenge: Leverage the power of Metasploit by creating a Metasploit module to easily scan multiple targets to determine whether the default administrative password is still active on the device.

The Prize: The first person to send us a working metasploit module (email/twitter) will win a free pass to our training course at 44Con and a limited edition anniversary t-shirt.

Good luck!

Wed, 8 Aug 2012

Privilege Escalation in SQL Server (Depending on some dodgy requirements)

I was playing with a few SQL server idiosyncrasies more than a year ago before becoming so completely distracted with the whole SAP protocol-decoding business. Having some time on my hands for once, I thought I would blog it.

Early last year, I found it possible to create jobs owned by other users on MS SQL Server (2000, 2005 and 2008) by an unprivileged user - providing the user had the capability of creating or altering stored procedures in the [master].[dbo] schema. The reason for this, comes as a result of cross-database permissions being chained, by default, across the system databases [master], [msdb] and [tempdb]. According to Microsoft, this is by design.

Where the issue comes in is that should a lower-privileged user have the capability of creating or altering stored procedures within [master].[dbo], it now becomes possible to insert records into the [msdb].[dbo].[sysjobs*] by executing the stored procedure - even without having any direct access to insert records into these tables. This is not particularly different from other system stored procedures (such as sp_addjob, for example) which allow users to create jobs, but the difference comes in in terms of the data we're allowed to populate.

SQL Server allows jobs and job steps to be executed under the context of specific user accounts. Whilst the majority of users (by default) are able to schedule jobs on the SQL Server, they can only schedule jobs which execute under their own account context and only members of the sysadmin server roles can add jobs which execute under the context of other user accounts. The underlying system stored procedures provided by Microsoft (sp_addjob and similar) prevent this functionality from being abused by lower privileged users. However, should it be possible to create/alter a stored procedure within [master].[dbo], we can insert records into the various [msdb] job tables with data of our choosing.

Hard-coding the [owner_sid] field in [msdb].[dbo].[sysjobs] to 0x01 (the default sid for the 'sa' user account) and the [database_user_name] field in [msdb].[dbo].[sysjobsteps] to 'sa' will allow us to create a job and associated job-step owned by the 'sa' user even though we are using an unprivileged account and do not have any permissions on the underlying tables.

In the following image, user eoppoc has no direct access to [msdb].[dbo].[sysjobs].

Executing a stored procedure, however, allows this access.

The following two images show the job created us user 'sa', with a single job step configured to execute as user 'sa'.

Honestly, I don't really see this as any form of issue. In order for it to be exploitable, there are far too many prerequisites and requirements and these prerequisites open other cans of worms. Furthermore, whilst one has the capability to schedule jobs to run as other users, one does not have the privilege level required to update the job cache. This means the newly created and scheduled job will only run after the SQL Server Agent has been restarted. It is nevertheless interesting and blog-worthy. And who knows, maybe this will be interesting / useful to somebody.

A zip file containing a procedure for SQL2000, and a procedure for SQL2005/2008 can be downloaded from here.

Oh - as a final note, Microsoft mentions that: "These databases are strictly system databases and is recommended not to create any user objects in these databases".


Thu, 2 Aug 2012

BlackOps – Post Exploitation Fun and Games

Brilliant, the client has decided to implement their own CMS and you've found a variable that's vulnerable to SQL injection. Starting up your favourite SQL exploitation tool, you upload a suitable web shell and fire up the browser. In an instant, you control that server, but do you really own the box?

Looking back at the major hacks of the last 18 months, attackers used a variety of techniques to obtain sensitive information. For the RSA hack, social engineering was used, allegedly consisting of a malicious Excel spreadsheet sent from a web master at a recruitment website. Once loaded, Poison Ivy was dropped on the host and the games began. Attackers started recon exercises, pivoting between hosts and finally exfiltrated the data (the rest is well-known and publicised). In the case of HBGary, attackers compromised their systems using a similar approach as the RSA attackers did: target an individual using social engineering using an earlier toehold to expand to a foothold. These types of attackers might have a fancy new name (Advanced Persistent Threats) but at the end of the day, they are using techniques that have been around for a while.

Owning a single host isn't the end of the journey, it's just the start.

At this year's 44Con, students will have the chance to learn how to take their offensive skills to the next level. Think of it as APT-style assessments.

Hacking By Numbers - BlackOps Edition will teach the next stage of the attack: lateral movement within a network, pivoting, and going after business relevant systems and data. Often, the juicier targets are buried deep inside the network, requiring complex tunnelling, evasion so as to not trigger alerts and finally, when you've accessed a target, ways to exfiltrate the data (spreadsheets via Facebook direct message, scp over a DNS tunnel, this can be fun).

The course looks at key areas of post-exploitation, and covers:

  • Working with big data on assessments
  • The difference between exploiting and owning a system
  • Effective ways to tunnel, pivot and exfiltrate data without being noticed
  • Owning systems using client-side attacks and social engineering
  • Privilege escalation
At the end of the course, students will participate in a final exercise set in a semi-real world environment, where they will need to used what they've learned compromise a target organisation, escalate privileges and tunnel sensitive data out from the network.

This course is aimed at making you think differently. It's offensive security at its best. To join this course, visit our booking page.