We are pleased to announce that we summarized the results from our VMDK research in our latest newsletter.
We hope you enjoy the reading and will get some “food for thought”!
The newsletter can be found at:
ERNW_Newsletter_41_ExploitingVirtualFileFormats.pd
A digitally signed version can be found at:
ERNW_Newsletter_41_ExploitingVirtualFileFormats_signed.pdf
Enjoy your weekend,
Matthias
Almost all of our presentations and write-ups on the VMDK File Inclusion Vulnerability contained a slide stating something like
“we’re rather sure that DoS is possible as well ;-)”
including the following screenshot of the ESX purple screen of death:
So it seems like we still owe you that one — sorry for the delay! However the actual attack to trigger this purple screen was rather simple: Just include multiple VMDK raw files that cannot be aligned with 512 Byte blocks — e.g. several files of 512 * X + [0 < Y < 512] Bytes. Writing to a virtual hard drive composed of such single files for a short amount of time (typically one to three minutes, this is what we observed in our lab) triggered the purple screen on both ESXi4 and ESXi5 — at least for a patch level earlier than Releasebuild-515841/March 2012: it seems like this vulnerability was patched in Patch ESXi500-201203201-UG.
Continue reading Continue readingIn our last series of posts regarding the VMDK file inclusion attack, we focused on read access and prerequisites for the attack, but avoided stating too much about potential write access. But as we promised to cover write access in the course of our future research, the following post will describe our latest research results.
First of all, the same prerequisites (which will be refined a little bit more later on) as for read access must be fulfilled and the same steps have to be performed in order to carry out the attack successfully. If that is the case, there are several POIs (Partitions Of Interest) on a ESXi hypervisor that are interesting to include:
Continue reading Continue readingAs we are receiving a lot of questions about our VMDK has left the building post, we’re compiling this FAQ post — which will be updated as our research goes on.
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How does the attack essentially work?
By bringing a specially crafted VMDK file into a VMware ESXi based virtualization environment. The specific attack path is described here.
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What is a VMDK file?
A combination of two different types of VMDK files, the plain-text descriptor file containing meta data and the actual binary disk file, describes a VMware virtual hard disk. A detailed description can be found here.
Continue reading Continue readingAs announced at last week’s #HITB2012AMS, I’ll describe the fuzzing steps which were performed during our initial research. The very first step was the definition of the interfaces we wanted to test. We decided to go with the plain text VMDK file, as this is the main virtual disk description file and in most deployment scenarios user controlled, and the data part of a special kind of VMDK files, the Host Sparse Extends.
Continue reading Continue reading