Clock Rollback Security for Offline Access

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Solution Overview

Problem

Existing systems are vulnerable to clock rollback attacks, where a malicious user can alter the system clock to bypass temporal restrictions, allowing unauthorized access to resources by tricking the system into thinking it is an earlier date and time.

Innovation Solution

Implement a method where the system checks and records the system time upon inactivity and compares it with the current time upon reactivation, taking remedial actions such as reauthentication or updating policies if the clock has been rolled back, to prevent further use until trust is reestablished.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the system relies on local system clock for determining current date/time in offline mode, then the device can access resources without continuous network connection, but the system becomes vulnerable to clock rollback attacks allowing unauthorized access

Engineering Contradiction:
Improveoffline access capabilityVSAvoidtemporal restriction enforcement
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary actions by storing the system time when the application goes inactive and comparing it with the current time upon reactivation. This proactive time tracking prevents clock rollback attacks by detecting time changes before they can be exploited for unauthorized access.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms by continuously monitoring system clock changes and triggering remedial actions (such as reauthentication or policy updates) when time rollback is detected. This closed-loop feedback ensures temporal restrictions remain enforceable even in offline mode.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the system allows manual changing of system clock, then the device provides user flexibility for time zone changes and scheduling, but enables malicious users to bypass temporal restrictions and access restricted resources

Engineering Contradiction:
Improveclock adjustment flexibilityVSAvoidunauthorized access vulnerability
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The system applies preliminary anti-action by preemptively detecting and responding to clock rollback attempts before they can be used for unauthorized access. By storing baseline time values and comparing subsequent time readings, the system counteracts potential malicious clock manipulation while still allowing legitimate time adjustments.

Inventive Principle:
Principle #9Preliminary anti-action

3Reliability

If the system implements strict temporal restrictions to prevent unauthorized access, then security is improved, but legitimate users may be blocked when their devices experience legitimate time changes or synchronization issues

Engineering Contradiction:
Improvesecurity enforcementVSAvoidlegitimate access flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system applies dynamics by making security enforcement adaptive rather than static. When clock rollback is detected, the system dynamically adjusts security measures (such as requiring reauthentication or updating policies from enterprise device management system) rather than immediately blocking all access. This dynamic response maintains security while accommodating legitimate time changes.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3611644B1Clock rollback security
Publication Date: 2021.01.20 CITRIX SYSTEMS INC
  • EP3611644B1 patent drawingFigure 1
  • EP3611644B1 patent drawingFigure 2
  • EP3611644B1 patent drawingFigure 3

AI summary

Methods and systems for preventing clock rollback attacks are described herein. A rollback attack may occur when a user manually sets a system clock to a date/time earlier than the actual present day date and time, thereby tricking any software relying on the system clock to believe it is in fact the earlier date and time rather than the current date and time. According to aspects described herein, a particular application may check and store a record of the system time when an application goes inactive (or at intervals) and again when the application subsequently is activated again. When the application determines that the time has gone backward, the application (or system) may take some remedial measure(s) to prevent further use of the application (or system) until the user reestablishes trust (e.g., by re-authenticating or reestablishing a connection with a trusted time server).