Attacker Value
Moderate
(2 users assessed)
Exploitability
Moderate
(2 users assessed)
User Interaction
Unknown
Privileges Required
Unknown
Attack Vector
Unknown
0

CVE-2019-12256 - VxWorks IPv4 Options Buffer Overflow

Disclosure Date: August 09, 2019 Last updated February 13, 2020
Add any MITRE ATT&CK Tactics to the list below that apply to this CVE.

Description

This vulnerability can be triggered by a specially crafted IP packet sent to the target device, even as a broadcast or multicast packet. It does not require any specific application or configuration to be running on the device, and it affects any device running VxWorks v6.9.4 or above with a network connection. The vulnerability causes a stack overflow in the handling of IP options in the IPv4 header, making it easy to reach RCE by it.

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3
Ratings
  • Attacker Value
    Very Low
  • Exploitability
    Very Low
Technical Analysis

Capability problems with exploitation: an attacker needs a payload to do something other than a DoS. Shellcode for embedded OSes like this needs to be customized for each firmware version and device, which causes problems. This significantly increases the cost for an attacker to do something other than a DoS since it has to be customized to the target. High utility for an advanced actor who has the capability to develop custom payloads and a particular target in mind. Low utility for a low-skilled actor who wants to ‘spray and pray’.

Mitigations: folks should limit opportunities by having strong malformed-packet filtering at the network level. Routers and switches should not be based on VxWorks at the edge.

https://www.blackhat.com/presentations/bh-usa-09/LINDNER/BHUSA09-Lindner-RouterExploit-SLIDES.pdf

Another interesting issue with this vulnerability lies around getting the malformed packets from the edge of a network into the core of the target device. Each device needs independent analysis to determine the risk. An edge device would be riskier than a core, one. In this particular case, it’s really surprising however that VxWorks did not just isic, which has been around for years and years to find a vulnerability like this: http://isic.sourceforge.net/

Note: when validating the Urgent/11 scanner here: https://github.com/ArmisSecurity/urgent11-detector we found that it was unlikely to be effective across even a minimal security boundary of a standard router between network segments. We had a hard time testing it since the malformed packets were discarded by several commodity and not specially-configured kit.

General Information

Additional Info

Technical Analysis