Trustwave SpiderLabs Security Advisory TWSL2018-011:
Use after free vulnerability in QFX Software KeyScrambler

Published: 10/03/2018
Version: 1.0

Vendor: QFX Software (https://www.qfxsoftware.com/ks-windows/)
Product: KeyScrambler
Version affected: <= 3.11

Product description:
KeyScambler is a kernel based keyboard driver encryption implementation
protecting the end-user against keylogger and key interception malware.
KeyScrambler encrypts every one of your keystrokes in real time ensuring that
everything you type on a website or a browser app is shielded from keylogging
attacks.

Finding: Kernel pointer double free/use-after-free (UAF)
Credit: Neil Kettle of Trustwave

An issue exists in the IOCTL handlers of the KeySrambler device whereby a local
user can cause a race condition to occur in the handling of a heap allocated
object potentially resulting in reading from or writing to unallocated memory
resulting in a Denial of Service condition or local code execution within the
context of the kernel.

Remediation Steps:
Upgrade to KeyScrambler, version 3.12 or the latest stable version. Please note
that Trustwave SpiderLabs have not verified this fix.

Revision History:
06/18/2018 - Vulnerability disclosed to vendor
09/08/2018 - Patch released by vendor
10/03/2018 - Advisory published

References
1. https://www.qfxsoftware.com/ks-windows/whats-new.htm

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About Trustwave SpiderLabs:
SpiderLabs(R) is the advanced security team at Trustwave focused on
application security, incident response, penetration testing, physical
security and security research. The team has performed over a thousand
incident investigations, thousands of penetration tests and hundreds of
application security tests globally. In addition, the SpiderLabs Research
team provides intelligence through bleeding-edge research and proof of
concept tool development to enhance Trustwave's products and services.
https://www.trustwave.com/spiderlabs

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