Bug 1886359 (CVE-2020-25651)

Summary: CVE-2020-25651 spice-vdagent: possible file transfer DoS and information leak via `active_xfers` hash map
Product: [Other] Security Response Reporter: Mauro Matteo Cascella <mcascell>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: alon, cfergeau, dblechte, hdegoede, marcandre.lureau, rh-spice-bugs, sandmann, security-response-team, uril
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: spice-vdagent 0.21.0 Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in the SPICE file transfer protocol. File data from the host system can partially or fully end up in the client connection of an unauthorized local user in the VM system. Active file transfers from other users could also be interrupted, resulting in a denial of service. The highest threat from this vulnerability is to confidentiality as well as system availability.
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Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Bug Depends On: 1886434, 1894434    
Bug Blocks: 1882815    

Description Mauro Matteo Cascella 2020-10-08 09:34:33 UTC 
A flaw was found in the SPICE file transfer protocol. It was reported by SUSE Security as follows:

The host application (tested with `remote-viewer` from the virt-viewer package) chooses an incrementally growing `task_id` for file exchanges
which starts counting at 1. Thus the `task_id` is predictable. Since any unauthenticated local client can replace the mapping of `task_id` to client
connection by its own client connection, there is a possibility for an attacker to obtain parts of the transferred file data.

File data from the host system can end up in full or in parts in the client connection of an illegitimate local user in the VM system. Exploitability will be difficult if there is not a suitable side channel with information about file transfers going on. In any case active file transfers from other users can also be interrupted (DoS aspect).
Comment 4 Mauro Matteo Cascella 2020-10-14 09:38:15 UTC 
Acknowledgments:

Name: Matthias Gerstner (SUSE Security Team)
Comment 5 Mauro Matteo Cascella 2020-11-04 09:34:29 UTC 
External References:

https://www.openwall.com/lists/oss-security/2020/11/04/1
Comment 6 Mauro Matteo Cascella 2020-11-04 09:35:14 UTC 
Created spice-vdagent tracking bugs for this issue:

Affects: fedora-all [bug 1894434]
Comment 7 Mauro Matteo Cascella 2020-11-09 09:22:08 UTC 
Upstream commits:
https://github.com/freedesktop/spice-vd_agent/commit/e4bfd1b632b6c14e8411dbe3565115a78cd3d256
https://github.com/freedesktop/spice-vd_agent/commit/b7db1c20c9f80154fb54392eb44add3486d3e427