AppSensor ResponseActions

About This Document

These response actions are part of the OWASP AppSensor project which advocates bringing intelligent intrusion detection inside the application. These responses can be used to counter a malicious user that has been detected probing for vulnerabilities or weaknesses within your application.

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Overview

The following table lists possible AppSensor Responses (ASRs). The application response actions are categorized here by:

• Silent: User(s) unaware of any application change
• Passive: Process altered, but user(s) may still continue to process completion
• Active: Functionality reduced or disabled

A text version of the table, with examples and alternative classifications, is described in AppSensor - Response Actions (64 KB PDF).

Detailed Listing

Classifications are:

• Purposes: Logging, Notifying, Disrupting and Blocking
• Target: One, Some or All users
• Response duration: Instantaneous (e.g. just for the request), Period (e.g. time period or session duration), Permanent

Silent

ASR-A: Logging Change

id	ASR-A
title	Logging Change
classifications	Logging | One, some or all users | Instantaneous (request) or for a period
category	Silent
description	The granularity of logging is changed (typically more logging).
consideration
examples	Example 1: Capture sanitised request headers and response bodies Example 2: Full stack trace of error messages logged Example 3: Record DNS data on user's IP address Example 4: Security logging level changed to include 'informational' messages
code	-

ASR-B: Administrator Notification

id	ASR-B
title	Administrator Notification
classifications	Logging and notifying | One, some or all users | Instantaneous
category	Silent
description	A notification message is sent to the application administrator(s)
consideration
examples	Example 1: Email alert sent to everyone in the administration team Example 2: SMS alert sent to the on-call administrator Example 3: Visual indicator displayed on an application monitoring dashboard Example 4: Audible alarm in the control room
code	-

ASR-C: Other Notification

id	ASR-C
title	Other Notification
classifications	Logging and notifying | One user | Instantaneous
category	Silent
description
consideration
examples	Example 1: Broadcast event to SIEM Example 2: Signal sent to network firewall Example 3: Alert sent to fraud protection department Example 4: Record added to server event log Example 5: Event highlighted in a daily management report Example 6: Email alert to staff member's manager Example 7: Proactive entry added to customer support system (e.g. "Someone had difficulty logging in with this customer's username - request extra validation for telephone enquiries")
code	-

ASR-D: User Status Change

id	ASR-D
title	User Status Change
classifications	Logging | One user | For a period
category	Passive
description
consideration
examples	Example 1: Internal trustworthiness scoring about the user changed Example 2: Reduce payment transfer limit for the customer before additional out-of-band verification is required Example 3: Reduce maximum file size limit for each file upload by the forum user Example 4: Increase data validation strictness for all form submissions by this citizen Example 5: Reduce the number of failed authentication attempts allowed before the user's account is locked (ASR-K below)
code	-

ASR-E: User Notification

id	ASR-E
title	User Notification
classifications	Logging, notifying and disrupting | One user | Instantaneous
category	Passive
description
consideration
examples	Example 1: On-screen message about mandatory form fields (e.g. "The 'occupation' must be completed") Example 2: On-screen message about data validation issues (e.g. 'The bank sort code can only contain six digits with optional hyphens') Example 3: Message sent by email to the registered email address to inform them their password has been changed
code	-

ASR-F: Timing Change

id	ASR-F
title	Timing Change
classifications	Logging and disrupting | One, some or all users | Instantaneous (request) or for a period
category	Passive
description
consideration
examples	Example 1: Extend response time for each failed authentication attempt Example 2: File upload process duration extended artificially Example 3: Add fixed time delay into every response Example 4: Order flagged for manual checking Example 5: Goods despatch put on hold (e.g. despatch status changed)
code	-

ASR-G: Process Terminated

id	ASR-G
title	Process Terminated
classifications	Logging, notifying (sometimes) and disrupting | One user | Instantaneous
category	Active
description
consideration
examples	Example 1: Discard data, display message and force user to begin business process from start Example 2: Redirection to log-in page Example 3: Redirection to home page Example 4: Display other content (i.e. terminate process but display the output of some other page without redirect)
code	-

ASR-H: Function Amended

id	ASR-H
title	Function Amended
classifications	Logging, notifying (sometimes), disrupting and blocking | One, some or all users | For a period or permanent
category	Active
description
consideration
examples	Example 1: Limit on feature usage rate imposed Example 2: Reduce number of times/day the user can submit a review Example 3: Additional registration validation steps Example 4: Additional anti-automation measures (e.g. out-of-band verification activated, CAPTCHA introduced) Example 5: Static rather than dynamic content returned Example 6: Additional validation requirements for delivery address Example 7: Watermarks added to pages, images and other content
code	-

ASR-I: Function Disabled

id	ASR-I
title	Function Disabled
classifications	Logging, notifying (sometimes), disrupting and blocking | One, some or all users | For a period or permanent
category	Active
description
consideration
examples	Example 1: 'Add friend' feature inactivated Example 2: 'Recommend to a colleague' feature links removed and disabled Example 3: Document library search disabled Example 4: Prevent new site registrations Example 5: Web service inactivated Example 6: Content syndication stopped Example 7: Automated Direct Debit system turned off and manual form offered instead
code	-

ASR-J: Account Logout

id	ASR-J
title	Account Logout
classifications	Logging, notifying (sometimes), disrupting and blocking | One user | Instantaneous
category	Active
description
consideration
examples	Example 1: Session terminated and user redirected to logged-out message page Example 2: Session terminated only (no redirect)
code	-

ASR-K: Account Lockout

id	ASR-K
title	Account Lockout
classifications	Logging, notifying (sometimes), disrupting and blocking | One user | For a period or permanent
category	Active
description
consideration
examples	Example 1: User account locked for 10 minutes Example 2: User account locked permanently until an Administrator resets it Example 3: One user's IP address range blocked Example 4: Unauthenticated user's session terminated
code	-

ASR-L: Application Disabled

id	ASR-L
title	Application Disabled
classifications	Logging, notifying (sometimes), disrupting and blocking | All users | Permanent
category	Active
description
consideration
examples	Example 1: Website shut down and replaced with temporary static page Example 2: Application taken offline
code	-

ASR-M: Collect Data from User

id	ASR-M
title	Collect Data from User
classifications	Logging | One user | For a period
category	Intrusive
description
consideration
examples	Example 1: Deploy additional browser fingerprinting using JavaScript in responses Example 2: Deploy a Java applet to collect remote IP address Example 3: Deploy JavaScript to collect information about the user's network
code	-