Date: Sat, 13 Jun 2015 11:17:05 +0200 From: Bastian Blank <waldi@...ian.org> To: oss-security@...ts.openwall.com Subject: CVE-2015-1850: OpenStack Cinder/Nova: Format-guessing and file disclosure in image convert Hi OpenStack Cinder and Nova do not provide input format to several calls of "qemu-img convert". In Cinder these calls are done as root. This allows the attacker to play the format guessing in qemu-img by providing input with a qcow2 signature. If this signature contains a base file, this file will be read by a process running as root and embedded in the output. This bug is similar to CVE-2013-1922 and has been assigned CVE-2015-1850. Tested with: lvm backed volume storage in Cinder, it may apply to others as well. Steps to reproduce: - create volume and attach to vm, - create a qcow2 signature on the volume containing a base-file from within the vm and - trigger an upload to Glance with "cinder upload-to-image --disk-type qcow2". The image uploaded to Glance will have the base-file from the cinder-volume host embedded. Affected versions: tested on 2014.1.3, found while reading 2014.2.1 Timeline: - Reported upstream 2015-01-27 - Published 2015-06-13 Regards, Bastian Blank : qemu-img create -f qcow2 -b /etc/passwd /dev/vdb : The disk-type != raw triggers the use of "qemu-img convert" -- You can't evaluate a man by logic alone. -- McCoy, "I, Mudd", stardate 4513.3
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