Synology DiskStation Manager arbitrary file modification

Overview

Synology DiskStation Manager versions 4.3-3776-3 and below contain a vulnerability that allows a remote unauthenticated user to append arbitrary data to an arbitrary file under root privileges.

Description

CWE-284: Improper Access Control - CVE-2013-6955

Synology DiskStation Manager versions 4.3-3776-3 and below allow a remote unauthenticated user to append arbitrary data to files on the system under root privileges. According to Synology:

Synology File Station in DSM employs a technique called “Slice Upload” to upload files when the file size is over 4GB [in the] Firefox browser. Since this feature is implemented in DSM4.0, all versions of DSM after DSM4.0 are subject to this vulnerability.

To exploit this vulnerability, an attacker needs to send a specially crafted HTTP POST request to /webman/imageSelector.cgi containing the header fields X-TYPE-NAME: SLICEUPLOAD and X-TMP-FILE with the valid path of the file to append malicious code or data.

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Impact

A remote unauthenticated attacker may be able to execute arbitrary code on the system under root privileges.

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Solution

Apply an Update

Synology has advised users to upgrade to the latest version of DiskStation Manager (DSM).

For Synology products released in 2008 (x08 series), DSM4.0-2259 has been released to address this issue.
For Synology products released after 2009, DSM4.2-3243 has been released to address this issue for DSM4.2 users. DSM4.3-3810 Update 1 has been released to address this issue for DSM4.3 users.

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Vendor Information

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Synology Affected

Notified: November 08, 2013 Updated: December 19, 2013

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

We are not aware of further vendor information regarding this vulnerability.

CVSS Metrics

Group	Score	Vector
Base	10	AV:N/AC:L/Au:N/C:C/I:C/A:C
Temporal	7.8	E:POC/RL:OF/RC:C
Environmental	2.0	CDP:L/TD:L/CR:ND/IR:ND/AR:ND

References

• <http://www.synology.com/en-us/dsm/index&gt;
• <http://www.synology.com/en-us/support/download&gt;

Acknowledgements

Thanks to Markus Wulftange for reporting this vulnerability.

This document was written by Todd Lewellen.

Other Information

CVE IDs:	CVE-2013-6955
Date Public:	2014-01-07 Date First Published: