Objects > Custom Objects > Spyware/Vulnerability

The firewall supports the ability to create custom spyware and vulnerability signatures using the firewall threat engine. You can write custom regular expression patterns to identify spyware phone home communication or vulnerability exploits. The resulting spyware and vulnerability patterns become available for use in any custom vulnerability profiles. The firewall looks for the custom-defined patterns in network traffic and takes the specified action for the vulnerability exploit.
Weekly content releases periodically include new decoders and contexts for which you can develop signatures.
You can optionally include a time attribute when defining custom signatures by specifying a threshold per interval for triggering possible actions in response to an attack. Action is taken only after the threshold is reached.
Use the Custom Spyware Signature page to define signatures for Anti-Spyware profiles. Use the Custom Vulnerability Signature page to define signatures for Vulnerability Protection profiles.
Custom Vulnerability and Spyware Signature Settings
Description
Configuration Tab
Threat ID
Enter a numeric identifier for the configuration (spyware signatures range is 15000-18000; vulnerability signatures range is 41000-45000).
Name
Specify the threat name.
Shared
Select this option if you want the custom signature to be available to:
  • Every virtual system (vsys) on a multi-vsys firewall. If you clear this selection, the custom signature will be available only to the Virtual System selected in the Objects tab.
  • Every device group on Panorama. If you clear this selection, the custom signature will be available only to the Device Group selected in the Objects tab.
Disable override (Panorama only)
Select this option to prevent administrators from overriding the settings of this signature in device groups that inherit the signature. This selection is cleared by default, which means administrators can override the settings for any device group that inherits the signature.
Comment
Enter an optional comment.
Severity
Assign a level that indicates the seriousness of the threat.
Default Action
Assign the default action to take if the threat conditions are met. For a list of actions, see Actions in Security Profiles .
Direction
Indicate whether the threat is assessed from the client to server, server to client, or both.
Affected System
Indicate whether the threat involves the client, server, either, or both. Applies to vulnerability signatures, but not spyware signatures.
CVE
Specify the common vulnerability enumeration (CVE) as an external reference for additional background and analysis.
Vendor
Specify the vendor identifier for the vulnerability as an external reference for additional background and analysis.
Bugtraq
Specify the bugtraq (similar to CVE) as an external reference for additional background and analysis.
Reference
Add any links to additional analysis or background information. The information is shown when a user clicks on the threat from the ACC, logs, or vulnerability profile.
Signatures Tab
Standard Signature
Select Standard and then Add a new signature. Specify the following information:
  • Standard—Enter a name to identify the signature.
  • Comment—Enter an optional description.
  • Ordered Condition Match—Select if the order in which signature conditions are defined is important.
  • Scope—Select whether to apply this signature only to the current transaction or to the full user session.
Add a condition by clicking Add Or Condition or Add And Condition. To add a condition within a group, select the group and then click Add Condition. Add a condition to a signature so that the signature is generated for traffic when the parameters you define for the condition are true. Select an Operator from the drop-down. The operator defines the type of condition that must be true for the custom signature to match to traffic. Choose from Less Than, Equal To, Greater Than, or Pattern Match operators.
  • When choosing a Pattern Match operator, specify for the following to be true for the signature to match to traffic:
    • Context—Select from the available contexts.
    • Pattern—Specify a regular expression. See Pattern Rules Syntax for pattern rules for regular expressions.
    • Qualifier and Value—Optionally, add qualifier/value pairs.
    • Negate—Select Negate so that the custom signature matches to traffic only when the defined Pattern Match condition is not true. This allows you to ensure that the custom signature is not triggered under certain conditions.
      A custom signature cannot be created with only Negate conditions; at least one positive condition must be included in order for a negate condition to specified. Also, if the scope of the signature is set to Session, a Negate condition cannot be configured as the last condition to match to traffic.
      You can define exceptions for custom vulnerability or spyware signatures using the new option to negate signature generation when traffic matches both a signature and the exception to the signature. Use this option to allow certain traffic in your network that might otherwise be classified as spyware or a vulnerability exploit. In this case, the signature is generated for traffic that matches the pattern; traffic that matches the pattern but also matches the exception to the pattern is excluded from signature generation and any associated policy action (such as being blocked or dropped). For example, you can define a signature to be generated for redirected URLs; however, you can now also create an exception where the signature is not generated for URLs that redirect to a trusted domain.
  • When choosing an Equal To, Less Than, or Greater Than operator, specify for the following to be true for the signature to match to traffic:
    • Context—Select from unknown requests and responses for TCP or UDP.
    • Position—Select between the first four or second four bytes in the payload.
    • Mask—Specify a 4-byte hex value, for example, 0xffffff00.
    • Value—Specify a 4-byte hex value, for example, 0xaabbccdd.
Combination Signature
Select Combination and specify the following information:
Select Combination Signatures to specify conditions that define signatures:
  • Add a condition by clicking Add AND Condition or Add OR Condition. To add a condition within a group, select the group and then click Add Condition.
  • To move a condition within a group, select the condition and click Move Up or Move Down. To move a group, select the group and click Move Up or Move Down. You cannot move conditions from one group to another.
Select Time Attribute to specify the following information:
  • Number of Hits—Specify the threshold that will trigger any policy-based action as a number of hits (1-1000) in a specified number of seconds (1-3600).
  • Aggregation Criteria—Specify whether the hits are tracked by source IP address, destination IP address, or a combination of source and destination IP addresses.
  • To move a condition within a group, select the condition and click Move Up or Move Down. To move a group, select the group and click Move Up or Move Down. You cannot move conditions from one group to another.

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