Configure malware scans and exclusions

Malware scan configurations are reusable saved settings that you can apply when configuring anti-malware in a policy or for a computer. A malware scan configuration specifies what types of malware scanning Deep Security performs and which files it scans. Some policy properties also affect the behavior of malware scans. You can perform the following:

The Deep Security Best Practice Guide also provides several recommendations for configuration of malware scans.

CPU usage and RAM usage varies by your anti-malware configuration. For information on how to optimize anti-malware performance in Deep Security Agent, see Performance tips for anti-malware.

Create or modify a malware scan configuration

You can create or modify one or more malware scan configurations to control the behavior of a real-time, manual, or scheduled scan. For more information, see Malware scan configurations.

  • After you create a malware scan configuration, you can then associate it with a scan in a policy or computer. For more information, see Select the types of scans to perform.
  • When you edit a malware scan configuration that a policy or computer is using, the changes affect the scans that are associated with the configuration.

To create a malware scan configuration that is similar to an existing one, duplicate the existing configuration and then edit it.

You can create two types of malware scan configurations according to the type of scan it controls (see Types of malware scans):

  • Real-time scan configuration: Controls real-time scans. Some actions such as Deny Access are only available for real-time scan configurations
  • Manual/scheduled scan configuration: Controls manual and scheduled scans. Some options such as CPU Usage are only available for manual and scheduled scan configurations.

Deep Security provides a default malware scan configuration for each type of scan. You can use this configuration as follows:

  1. Go to Policies > Common Objects > Other > Malware Scan Configurations.
  2. To create a scan configuration, click New, click New Real-Time Scan Configuration or New Manual/Scheduled Scan Configuration, and then:
    1. Type a name to identify the scan configuration. You see the name in a list when configuring malware scans in a policy.
    2. Optionally, type a description that explains the use case for the configuration.
  3. To view and edit an existing scan configuration, select it and click Properties.
  4. To duplicate a scan configuration, select it and click Duplicate.

To see the policies and computers that are using a malware scan configuration, see the Assigned To tab of the properties.

Test malware scans

Before continuing with Anti-Malware configuration steps, test scans to ensure they are working correctly.

To test a real-time scan:

  1. Make sure the real-time scan is enabled and that a configuration is selected.
  2. Go to the EICAR site and download their anti-malware test file. This standardized file tests the real-time scan's anti-virus capabilities. The file should be quarantined.
  3. On Deep Security Manager, go to Events & Reports > Anti-Malware Events to verify the record of the EICAR file detection. If the detection is recorded, the Anti-Malware real-time scans are working correctly.

To test a manual or scheduled scan:

  1. Make sure the real-time scan is disabled.
  2. Go to Administration.
  3. Click Scheduled tasks > New.
  4. Select Scan Computers for Malware from the menu and select frequency. Complete the scan configuration with your desired specifications.
  5. Go to the EICAR site and download their anti-malware test file. This standardized file tests the manual or scheduled scan's anti-virus capabilities.
  6. Select the scheduled scan and click Run Task Now. The test file should be quarantined.
  7. On Deep Security Manager, go to Events & Reports > Anti-Malware Events to verify the record of the EICAR file detection. If the detection is recorded, the Anti-Malware manual and scheduled scans are working correctly.

Scan for specific types of malware

See also:

Enable Windows AMSI protection (real-time scans only)

The Windows Antimalware Scan Interface (AMSI) is an interface provided by Microsoft in Windows 10 and newer. Deep Security leverages AMSI to help detect malicious scripts. By default, this option is enabled in Deep Security malware scan configurations.

  1. Open the properties of the malware scan configuration.
  2. On the General tab, select Enable AMSI protection.
  3. Click OK.

Scan for spyware and grayware

When spyware and grayware protection is enabled, the spyware scan engine quarantines suspicious files when they are detected.

  1. Open the properties of the malware scan configuration.
  2. On the General tab, select Enable spyware/grayware protection.
  3. Click OK.

To identify a file that the spyware scan engine should ignore, see Configure advanced exploit exceptions.

Scan for compressed executable files (real-time scans only)

Viruses often use real-time compression algorithms to attempt to circumvent virus filtering. The IntelliTrap feature blocks real-time compressed executable files and pairing them with other malware characteristics.

Because IntelliTrap identifies such files as security risks and may incorrectly block safe files, consider quarantining (not deleting or cleaning) files when you enable IntelliTrap. For more information, see Configure malware handling. If the exchange of real-time compressed executable files is performed regularly, disable IntelliTrap. IntelliTrap uses the virus scan engine, IntelliTrap Pattern, and IntelliTrap Exception Pattern.

  1. Open the properties of the malware scan configuration.
  2. On the General tab, select Enable IntelliTrap.
  3. Click OK.

Scan process memory

Monitor process memory and perform additional checks with the Trend Micro Smart Protection network to determine whether or not a suspicious process is known to be malicious. If the process is malicious, Deep Security terminates the process. For more information, see Smart Protection in Deep Security

  1. Open the properties of the malware scan configuration.
  2. On the General tab, select Scan process memory for malware.
  3. Click OK.

With Deep Security Agent version 20.0.1-12510 and later, you can use Action to take to select the remediation action that Deep Security takes when it detects malware. The recommended value is ActiveAction. Or you could select Pass. For more information, see ActiveAction actions and Customize malware remedial actions

Scan compressed files

Extract compressed files and scan the contents for malware. When you enable the scan, you specify the maximum size and number of files to extract (large files can affect performance). You also specify the levels of compression to inspect so that you can scan compressed files that reside inside compressed files. Level 1 compression is a single compressed file. Compressed files inside that file are level two. You can scan a maximum of 6 compression levels, however higher levels can affect performance.

  1. Open the properties of the malware scan configuration.
  2. On the Advanced tab, select Scan compressed files.
  3. Specify the maximum size of content files to extract, in MB, the levels of compression to scan, and the maximum number of files to extract.
  4. Click OK.

Scan embedded Microsoft Office objects

Certain versions of Microsoft Office use Object Linking and Embedding (OLE) to insert files and other objects into Office files. These embedded objects can contain malicious code.

Specify the number of OLE layers to scan to detect objects that are embedded in other objects. To reduce the impact on performance, you can scan only a few layers of embedded objects within each file.

  1. Open the properties of the malware scan configuration.
  2. On the Advanced tab, select Scan Embedded Microsoft Office Objects.
  3. Specify the number of OLE layers to scan.
  4. Click OK.

Enable a manual scan for the notifier application on Windows OS

Enabling a manual scan through the Trend Micro notifier application is supported for Deep Security Agents 20.0.0-7476 and later.

This scan is disabled by default. You can enable and trigger it as follows:

  1. From the Computer or Policy editor, select Anti-Malware > General.
  2. Under Manual Scan, select Allow the agent to trigger or cancel a manual scan.

Note that agentless scans are not supported.

Enable a manual scan on Linux OS

Enabling a manual scan is supported for Deep Security Agents 20.0.0-7476 and later.

This scan is disabled by default. You can enable it as follows:

  1. From the Computer or Policy editor, select Anti-Malware > General.
  2. Under Manual Scan, select Allow the agent to trigger or cancel a manual scan.

Note that agentless scans are not supported.

Specify the files to scan

Identify files and directories to include in the scan and then identify any exclusions from those files and directories. You can also scan network directories.

Inclusions

Specify the directories to scan as well as the files inside the directories to scan.

To identify directories to scan, you can specify all directories or a list of directories. The directory list uses patterns with a specific syntax to identify the directories to scan. For more information, see Syntax for directory lists.

To identify the files to scan, use one of the following options:

  • All files
  • File types that are identified by IntelliScan. IntelliScan only scans file types that are vulnerable to infection, such as .zip or .exe. IntelliScan does not rely on file extensions to determine file type but instead reads the header and content of a file to determine whether it should be scanned. Compared to scanning all files, Intelliscan reduces the number of files to scan and improves performance.
  • Files that have a file name extension that is included in a specified list: The file extension list uses patterns with a specific syntax. For more information, see Syntax of file extension lists.
  1. Open the properties of the malware scan configuration.
  2. Click the Inclusions tab.
  3. To specify the directories to scan, select All directories or Directory List.
  4. If you selected Directory List, from the drop-down menu either select an existing list or select New to create one.
  5. To specify the files to scan, select either All files, File types scanned by IntelliScan, or File Extension List.
  6. If you selected File Extension List, from the menu either select an existing list or select New to create one.
  7. Click OK.

Exclusions

Exclude directories, files, and file extensions from being scanned. For real-time scans (except when performed by Deep Security Virtual Appliance), you can also exclude process image files from being scanned.

The following are examples of files and folders to exclude:

  • If you are creating a malware scan configuration for a Microsoft Exchange server, you should exclude the SMEX quarantine folder to avoid re-scanning files that have already been confirmed to be malware.
  • If you choose to run malware scans on database servers used by Deep Security Manager, exclude the data directory. The Deep Security Manager captures and stores intrusion prevention data that might include viruses, which can trigger a quarantine by the Deep Security Agent, leading to database corruption.
  • If you have large VMware images, exclude the directory containing these images if you experience performance issues.

You can also exclude files from Anti-Malware scanning when they are signed by a trusted digital certificate. This type of exclusion is defined in policy or computer settings. For more information, see Exclude files signed by a trusted certificate.

Exclude directories, files, and process image files by creating a list of patterns to exclude

  1. Open the properties of the malware scan configuration.
  2. Click the Exclusions tab.
  3. Specify the directories to exclude:
    1. Select Directory List.
    2. Select a directory list or select New to create one. For more information, see Syntax for directory lists.
    3. If you created a directory list, select it in the directory list.
  4. Similarly, specify the file list, file extension list, and process image file list to exclude. For more information, see Syntax of file lists, Syntax of file extension lists, and Syntax of process image file lists)
  5. Click OK.

When Deep Security Agent cannot determine the type of a target file, the Anti-Malware scan engine loads the file to memory to identify if it was a self-extracting file. If many large files are loaded to memory, it can affect scan engine performance. To exclude files over a specific size, you can use the following Deep Security Manager command:

dsm_c -action changesetting -name com.trendmicro.ds.antimalware:settings.configuration.maxSelfExtractRTScanSizeMB -value 512

In this example, the file-size limitation is set to 512 MB for loading target files. The scan engine does not add files larger than the set value to memory and instead scans them directly. Note that in order to deploy this setting, you need to send the policy to your target Deep Security Agent after running the command in Deep Security Manager.

Test file exclusions

Before continuing with further Anti-Malware configuration steps, test file exclusions to ensure they are working correctly:

  1. Make sure the real-time scan is enabled and a configuration is selected.
  2. Go to Policies > Common Objects > Other > Malware Scan Configurations.
  3. Click New > New Real-time Scan Configuration.
  4. Go to the Exclusions tab, and select New from the directory list.
  5. Name the directory list.
  6. Under Directorys specify the path of the directory you want to exclude from the scan. For example, c:\Test Folder\.
  7. Click OK .
  8. Go to the General tab, name the manual scan, and click OK.
  9. Go to the EICAR site and download their anti-malware test file. Save the file in the folder specified in the previous step. The file should be saved and undetected by the Anti-Malware module.

Syntax for directory lists

Directory list items accept either forward slash or backslash to support both Windows and Linux conventions.

Exclusion Format Description Examples
Directory DIRECTORY\ Excludes all files in the specified directory and all files in all subdirectories. C:\Program Files\
Excludes all files in the Program Files directory and all subdirectories.
Directory with wildcard (*) DIRECTORY\*\ Excludes all subdirectories except for the specified subdirectory and the files that it contains. C:\abc\*\
Excludes all files in all subdirectories of abc but does not exclude the files in the abc directory.

C:\abc\wx*z\
Matches:
C:\abc\wxz\
C:\abc\wx123z\
Does not match:
C:\abc\wxz
C:\abc\wx123z

C:\abc\*wx\
Matches:
C:\abc\wx\
C:\abc\123wx\
Does not match:
C:\abc\wx
C:\abc\123wx
Directory with wildcard (*) DIRECTORY*\ Excludes any subdirectories with a matching name, but does not exclude the files in that directory and any subdirectories. C:\Program Files\SubDirName*\

Excludes any subdirectories with a folder name that begins with SubDirName. Does not exclude all files under C:\Program Files\ or any other subdirectories.

 
Environment variable ${ENV VAR} Excludes all files and subdirectories defined by an environment variable. For a Virtual Appliance, the value pairs for the environment variable must be defined in Policy or Computer Editor > Settings > General > Environment Variable Overrides. ${windir}
If the variable resolves to c:\windows, excludes all the files in c:\windows and all its subdirectories.
Comments DIRECTORY #Comment Adds a comment to your exclusion definitions. c:\abc #Exclude the abc directory

Syntax of file lists

Exclusion Format Description Example
File FILE Excludes all files with the specified file name regardless of its location or directory. abc.doc
Excludes all files named abc.doc in all directories. Does not exclude abc.exe.
File path FILEPATH Excludes the single file specified by the file path. C:\Documents\abc.doc
Excludes only the file named abc.doc in the Documents directory.
File path with wildcard (*) FILEPATH Excludes all the files specified by the file path. C:\Documents\abc.co* (For Windows Agent platforms only) Excludes any file that has file name of abc and extension beginning with .co in the Documents directory.
Filename is a wildcard (*) FILEPATH\* Excludes all files under the path, but does not include the files in unspecified subdirectories C:\Documents\*
Excludes all files under the directory C:\Documents\

C:\Documents\SubDirName*\*
Excludes all files within subdirectories with a folder name that begins with SubDirName. Does not exclude all files under C:\Documents\ or any other subdirectories.

C:\Documents\*\*
Excludes all files within all direct subdirectories under C:\Documents. Does not exclude files in subsequent subdirectories.
File with wildcard (*) FILE* Excludes all files with a matching pattern in the file name. abc*.exe
Excludes any file that has prefix of abc and extension of .exe.

*.db
Matches:
123.db
abc.db
Does not match:
123db
123.abd
cbc.dba

*db
Matches:
123.db
123db
ac.db
acdb
db
Does not match:
db123

wxy*.db
Matches:
wxy.db
wxy123.db
Does not match:
wxydb
File with wildcard (*) FILE.EXT* Excludes all files with a matching pattern in the file extension. abc.v*
Excludes any file that has file name of abc and extension beginning with .v.

abc.*pp
Matches:
abc.pp
abc.app
Does not match:
wxy.app

abc.a*p
Matches:
abc.ap
abc.a123p
Does not match:
abc.pp

abc.*
Matches:
abc.123
abc.xyz
Does not match:
wxy.123
File with wildcard (*) FILE*.EXT* Excludes all files with a matching pattern in the file name and in the extension. a*c.a*p
Matches:
ac.ap
a123c.ap
ac.a456p
a123c.a456p
Does not match:
ad.aa
Environment variable ${ENV VAR} Excludes files specified by an environment variable with the format ${ENV VAR}. These can be defined or overridden using Policy or Computer Editor > Settings > General > Environment Variable Overrides. ${myDBFile}
Excludes the file myDBFile.
Comments FILEPATH #Comment Adds a comment to your exclusion definitions. C:\Documents\abc.doc #This is a comment

Syntax of file extension lists

Exclusion Format Description Example
File Extension EXT Matches all files with a matching file extension. doc
Matches all files with a .doc extension in all directories.
Comments EXT #Comment Adds a comment to your exclusion definitions. doc #This a comment

Syntax of process image file lists

Exclusion Format Description Example
File path FILEPATH Excludes the Process Image file specified by the file path. C:\abc\file.exe
Excludes only the file named file.exe in the abc directory.

Scan a network directory (real-time scan only)

If you want to scan files and folders in network shares and mapped network drives that reside in a Network File System (NFS), Server Message Block (SMB) or Common Internet File System (CIFS), select Enable Network Directory Scan. This option is available only for real-time scans.

Resources accessed in "~/.gvfs" via GVFS, a virtual file system available for the GNOME desktop, are treated as local resources, as opposed to network drives.

If a virus is detected when scanning a network folder on Windows, the agent may display some clean failed (delete failed) events.

Specify when real-time scans occur

Choose between scanning files when they are opened for reading, when they are written to, or both.

  1. Open the properties of the malware scan configuration.
  2. On the Advanced tab, select one of the options for the Real-Time Scan property.
  3. Click OK.

Configure malware handling

Configure how Deep Security behaves when malware is detected:

Customize malware remedial actions

When Deep Security detects malware, it performs a remedial action to handle the file. There are five possible actions that Deep Security can take when it encounters malware:

  • Pass: Allows full access to the infected file without doing anything to the file. An Anti-Malware Event is still recorded. The remedial action Pass should never be used for a possible virus.
  • Clean: Cleans an infected file before allowing full access to it. If the file cannot be cleaned, it is quarantined.
  • Delete: On Linux, the infected file is deleted without a backup. On Windows, the infected file is backed up and then deleted. Windows backup files can be viewed and restored in Events & Reports > Events > Anti-Malware Events > Identified Files.
  • Deny Access: This scan action can only be performed during real-time scans. When Deep Security detects an attempt to open or execute an infected file, it immediately blocks the operation. The infected file is left unchanged. When the Access Denied action is triggered, the infected files stay in their original location. Do not use the remedial action Deny Access when Real-Time Scan is set to During Write. When During Write is selected, files are scanned when they are written and the action Deny Access has no effect.
  • Quarantine: Moves the infected file to the quarantine directory on the computer or Virtual Appliance. The quarantined file can be viewed and restored in Events & Reports > Events > Anti-Malware Events > Identified Files.

    Malware marked as Quarantined on Linux might be marked as Deleted on Windows, despite the malware being identical on both operating systems. In either case, the file can be viewed and restored in Events & Reports > Events > Anti-Malware Events > Identified Files.

    On Windows, infected non-compressed files (for example, .txt files) are quarantined, while infected compressed files (for example, .zip files) are deleted. On Windows, both quarantined or deleted files have a backup that can be viewed and restored in Events & Reports > Events > Anti-Malware Events > Identified Files. On Linux, all infected files (compressed or non-compressed) are quarantined, and can be viewed and restored in Events & Reports > Events > Anti-Malware Events > Identified Files.

The default remediation actions in the malware scan configurations are appropriate for most circumstances. However, you can customize the actions to take when Deep Security detects malware. You can either use the action that ActiveAction determines, or specify the action for each type of vulnerability.

ActiveAction is a predefined group of cleanup actions that are optimized for each malware category. Trend Micro continually adjusts the actions in ActiveAction to ensure that individual detections are handled properly. See ActiveAction actions.

  1. Open the properties of the malware scan configuration.
  2. On the Advanced tab, for Remediation Actions select Custom.
  3. Specify the action to take:
    1. To let ActiveAction decide which action to take, select Use action recommended by ActiveAction.
    2. To specify an action for each type of vulnerability, select Use custom actions, and then select the actions to use.
  4. Specify the action to take for Possible Malware.
  5. Click OK.

ActiveAction actions

The following table lists the actions that ActiveAction takes:

Malware Type Action
Virus

Clean. If a virus cannot be cleaned, it is deleted (Windows) or quarantined (Linux or Solaris). There is an exception to this behavior: On a Linux or Solaris agent, if a virus of type Test Virus is found, access is denied to the infected file.

Trojans Quarantine
Packer Quarantine
Spyware/grayware Quarantine
CVE Exploit Quarantine
Aggressive Detection Rule Pass
This setting detects more issues but may also result in more false positives, so the default action is to raise an event.
Cookie Delete
Does not apply to real-time scans
Other threats

Clean

If a threat cannot be cleaned, it is handled as follows:

Also, on a Linux or Solaris agent, if a virus of type 'Joke' is found, it is quarantined immediately. No attempt is made to clean it.
Possible malware ActiveAction

When the agent downloads virus pattern updates from an ActiveUpdate server or relay, it may change its ActiveAction scan actions.

For information about CVE Exploit and Aggressive Detection Rule, see Create a malware scan configuration for use with Threat Intelligence.

Generate alerts for malware detection

When Deep Security detects malware, you can generate an alert:

  1. Open the properties of the malware scan configuration.
  2. On the General tab, for Alert select Alert when this Malware Scan Configuration logs an event.
  3. Click OK.

Apply NSX security tags

Deep Security can apply NSX Security Tags to protected VMs upon detecting a malware threat. For details, see Configure Anti-Malware to apply NSX security tags.

Identify malware files by file hash digest

Deep Security can calculate the hash value of a malware file and display it on the Events & Reports > Events > Anti-Malware Events page. Because a particular piece of malware can go by several different names, the hash value is useful because it uniquely identifies the malware. You can use the hash value when looking up information about the malware from other sources.

  1. Open the policy or computer editor that you want to configure.
  2. Click Anti-Malware > Advanced.
  3. Under File Hash Calculation, clear the Default or Inherited check box. Default is displayed for a root policy and Inherited is displayed for child policies.

    When Inherited is selected, the file hash settings are inherited from the current policy's parent policy.

    When Default is selected, Deep Security does not calculate any hash values.

  4. Select the Calculate hash values of all anti-malware events.
  5. By default, Deep Security will produce SHA-1 hash values. If you want to produce additional hash values, you can select one or both of MD5 and SHA256.
  6. You can also change the maximum size of malware files that will have hash values calculated. The default is to skip files that are larger than 128MB, but you can change the value to anything between 64 and 512 MB.

Configure notifications on the computer

On Windows-based agents, you might occasionally see onscreen notification messages alerting you of Deep Security actions you must take that are related to the anti-malware and web reputation modules. For example, you might see the message, A reboot is required for Anti-Malware cleanup task. You must click OK on the dialog box to dismiss it.

If you do not want these notifications to appear:

  1. Go to the Computer or Policy editorClosedYou can change these settings for a policy or for a specific computer. To change the settings for a policy, go to the Polices page and double-click the policy that you want to edit (or select the policy and click Details). To change the settings for a computer, go to the Computers page and double-click the computer that you want to edit (or select the computer and click Details)..
  2. Click Settings on the left.
  3. Under the General tab, scroll to the Notifications section.
  4. Set Suppress all pop-up notifications on host to Yes. The messages still appear as alerts or events in Deep Security Manager. For more information about the notifier, see Deep Security notifier.