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Configuring the scheduled scan

 

Applies to: Forefront Protection for Exchange

Topic Last Modified: 2010-07-07

There are various configuration settings that you can adjust for the scheduled scan in order to meet the needs of your environment. These include selecting the number of scan engines to use for each scan, setting the action to take when malware is detected, and specifying whether or not to quarantine detected files.

To configure the scheduled scan
  1. In the Forefront Protection 2010 for Exchange Server Administrator Console, click Policy Management and under Antimalware, click Mailbox - Scheduled.

  2. In the Antimalware - Mailbox Scheduled pane, under the General Settings section, configure the following settings:

    1. Enable scheduled antivirus scan—Select or clear this check box to enable or disable the scheduled antivirus scan. This setting is enabled by default.

    2. Enable scheduled antispyware scan—Select or clear this check box to enable or disable the scheduled antispyware scan. This setting is enabled by default.

  3. In the Antimalware - Mailbox Scheduled pane, under the Engines and Performance section, select the number of scan engines that should be used for this scan. For more information, see Configuring the number of scan engines used for each scan.

  4. In the Antimalware - Mailbox Scheduled pane, under the Scan Actions section, configure the following settings:

    1. Action—Select the action that you want performed when a virus or spyware is detected. For virus detections, you can select Skip detect, Clean (the default), and Delete. For spyware detections, you can select Skip detect, Delete (the default), and Purge. For more information, see Configuring the action when malware is detected.

    2. Quarantine Files—Using the drop-down list, enable (by selecting Yes) or disable (by selecting No) saving infected files detected by the file-scanning engines. Quarantining is enabled by default. Enabling quarantine causes deleted attachments and purged messages to be stored in a secure location, from which you can recover them. However, worm-purged messages are not recoverable. For more information about quarantine, see Viewing and managing quarantine.

    3. Edit Malware Deletion Text—You can specify deletion text, which is used to replace the contents of an infected file during a delete operation. The default deletion text informs you that an infected file was removed, along with the name of the file and the name of the malware found. To change the default deletion text, click Edit Malware Deletion Text, make the modifications to the deletion text in the Edit Malware Deletion Text dialog box, and then click Apply and Close to return to the Antimalware - Mailbox Scheduled pane.

      NoteNote:
      FPE provides keywords that can be used in the deletion text field to obtain information from the message in which the infection was found. To use them, in the Edit Malware Deletion Text dialog box, right-click, select Insert Field, and then select the desired macro. For more information about this feature, see Keyword substitution macros.
  5. Click Save.

NoteNote:
The Schedule options are described in Scheduling the scheduled scan.

You can configure the following additional settings located under the Additional Options section of the Antimalware - Mailbox Scheduled pane. Click Save after making any changes to your settings.

  • Scan doc files as containers—Configures the scheduled scan to scan files that use structured storage and the OLE embedded data format (for example, .doc, .xls, .ppt, or .shs) as container files. This ensures that any embedded files are scanned as potential malware carriers. This setting is disabled by default.

  • Scan message body—Configures the scheduled scan to scan message bodies as well as attachments. Scanning message bodies is disabled by default because message-body scanning increases the time required to perform a scan.

    ImportantImportant:
    When you enable the Scan message body setting for the scheduled scan, you must also disable the scheduled scan setting Scan only messages with attachments (it is enabled by default). Otherwise, message bodies will only be scanned for messages that also have attachments.
  • Start scheduled scan after engine update—Configures the scheduled scan to run immediately after an engine or definition update, regardless of when it is next scheduled to run. This setting is disabled by default.

    CautionCaution:
    When this setting is enabled and an update occurs while a scheduled scan is in progress, the scheduled scan restarts at the mail that was being scanned. If updates continue to occur before the scheduled scan finishes, the scan continues to run indefinitely. It is therefore recommended that you do not schedule a scan for a large dataset if this setting is enabled. Also note that when this option is enabled, the mailbox server may experience increased malware scanning, which may impact server performance.
  • Suppress malware notifications—Suppresses the sending of Virus found, Spyware found, and Worm found notifications, even if these notifications are enabled. This setting is disabled by default.

  • Process count—Configures the number of processes you want running per mailbox server. The default value is 1; the maximum value is 10.

    More than the default number of processes should not be necessary, except in high-volume environments. Scheduled scan performance may be improved by increasing the number of processes, but be aware that each additional process will consume additional system resources which could impact the performance of the mailbox server. When increasing this setting, you should closely monitor resource consumption and performance prior to making additional adjustments.

    When multiple scheduled processes are running, the first process scans the file unless it is busy; in which case, the file is delivered to the second process for scanning. If the second process is busy and a third is enabled, the third process scans the file. When the server runs out of scanning processes to use, the scan is queued until a scanning process becomes available.

    ImportantImportant:
    You must stop and then start the Microsoft Exchange Information Store service in order for changes to this setting to take effect. Do not use the Restart function. (This service must be recycled because the updated settings are incorporated by the Forefront hook that is loaded by the Exchange Information Store service.)
  • Scanning timeout (seconds)—Configures the number of seconds that the scheduled scan scans a file before timing out. The default value is 150 seconds.

    In the event that the scheduled scan exceeds the specified time to scan a message, the process is terminated, and FPE attempts to restart the service. If successful, scheduled scanning resumes and a notification is sent to the administrator stating that the scheduled scan exceeded the allotted scan time and was recovered.

    When the new scheduled scan process starts, the message that caused it to terminate is reprocessed according to the Scan timeout action setting. For example, if it is set to Delete, FPE deletes the file, replaces its contents with the deletion text for the scheduled scan, logs the information, and quarantines and archives the file.

    If the process cannot be restarted, a notification is sent to the administrator stating that the scheduled scan stopped. In this event, scheduled scanning for the particular storage group does not function, but the information store does not stop.

    ImportantImportant:
    You must stop and then start the Microsoft Exchange Information Store service in order for changes to this setting to take effect. Do not use the Restart function. (This service must be recycled because the updated settings are incorporated by the Forefront hook that is loaded by the Exchange Information Store service.)
  • Scan timeout action—Configures what action to take when the scheduled scan times out while scanning a file. The options are the following:

    • Ignore—Lets the file pass without being scanned.

    • Skip detect—Reports in the Incidents log and the Program log that the file exceeded the scan time and lets it pass without being scanned.

    • Delete—Reports the event and replaces the contents of the file with the deletion text. Delete is the default value.

    NoteNote:
    If the Scan timeout action is set to Skip detect or Delete, and if quarantining is enabled, then a copy of the file is stored in the database.
  • Maximum container scan time (seconds)—Configures the number of seconds that the scheduled scan scans a compressed attachment before reporting it as a ScanTimeExceeded incident. This option is intended to prevent the risk of denial of service due to zip-of-death attacks. The default value is 120 seconds.

You can configure the following additional settings located under the Scheduled Scan Settings section of the Antimalware - Mailbox Scheduled pane. Click Save after making any changes to your settings.

  • Scan only unscanned messages—Configures the scheduled scan to only scan messages that have not yet been scanned. This setting is disabled by default.

  • Scan only messages with attachments—Configures the scheduled scan to scan only messages that include attachments. This setting is enabled by default.

  • Enable maximum scan time—Selecting this check box enables you to specify the maximum time that the scheduled scan runs before timing out. This setting is disabled (cleared) by default, meaning that there is no scan time limit. If selected, set the time with the Maximum scan time (hours: minutes) option.

  • Maximum scan time (hours: minutes)—If you enabled the Enable maximum scan time setting, use this setting to specify the maximum time, in hours and minutes, that the scheduled scan will run before timing out. When enabled, the default setting is 1 hour. The maximum time that you can specify is 23 hours and 59 minutes.

  • Scan only messages received in the last—Places limits on scheduled scanning by configuring the scheduled scan to scan messages based on their age. In the drop-down list, click one of the following options: Anytime, 4 hours, 6 hours, 8 hours, 12 hours, 18 hours, 1 day, 2 days (the default), 3 days, 4 days, 5 days, 6 days, 7 days, 30 days.

    ImportantImportant:
    Use caution when setting this option. If the message arrival rate at the mailbox server is very high and too long a scan back period is selected, scheduled scanning may run continuously, which can have a negative impact on server performance.

    The selected scan back period should be set based on an understanding of a specific threat or in order to generally cover the always-present protection gap between when malware may have been released and the availability of protection definitions. If scanning is scheduled to run on a daily basis (for more information, see Scheduling the scheduled scan), the recommended setting is to scan the previous two days' worth of mail. However, the time should be set based on both security and performance considerations.

  • Set priority—Sets the CPU priority of the scheduled scan. In the Set priority drop-down list, click one of the following: Normal (the default), Below normal, or Low. Changing the value to Below normal or Low enables more important jobs to take precedence over the scheduled scan when demands on server resources are high.

 
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