How To: Restore Zimbra Quarantined Email by Clam AKA Heuristics.Encrypted.PDF Release Point

Zimbra Mail Server automatically quarantines emails that get hit by the Antivirus scan using Clam when the mail is received. While putting the email on the recipient inbox, what it does, instead of giving the original email with the attachment, it sends a virus detected email with the following kind of error message:

Virus (Heuristics.Encrypted.PDF) in mail to YOU

Virus Alert
Our content checker found
virus: Heuristics.Encrypted.PDF

by Zimbra

It actually means, the original mail is now quarantined. Zimbra maintains a virus quarantine email account that is not normally available in the ‘Manage Account’ list of Zimbra Admin panel. You can find it if you search with ‘virus’ in the ‘Search’ box of the admin panel. What zimbra does in quarantine situation, is that, it pushes the mail to the quarantine email instead of original recipient.

Now, to get back the mail delivered to the original recipient, we need to first get the quarantine email account, get the message id, and then we need to inject the mail into the LMTP pipe that bypasses any scanning. Here are the steps on how to do this:

# First get to the zimbra user
$ su - zimbra

# Get the email account that is used to store virus detected mails
$ zmprov gcf zimbraAmavisQuarantineAccount
zimbraAmavisQuarantineAccount: virus-quarantine.mrhmcbg4kz@yourhostname.com

# virus-quarantine.mrhmcbg4kz@yourhostname.com this should be our quarantine email account, now we need to get the quarantine account's mailbox id
$ zmprov gmi virus-quarantine.mrhmcbg4kz@yourhostname.com
mailboxId: 73
quotaUsed: 644183

# Mailbox id here for the quarantine account is 73. Now go to the message storage of this id using the following command: cd /opt/zimbra/store/0/<mailboxId>/msg/0
$ cd /opt/zimbra/store/0/73/msg/0

# list the messages
$ ls *

These are your quarantined emails. Now for example the complainer is ‘sam@yourhostname.com’. To search for the emails designated for this email account, you may use the following:

$ grep -l sam@yourhostname.com *
281-1216.msg
300-1400.msg
301-1476.msg

This should return you all the emails that got quarantined for the above user.

Now the question is, how can we get these emails delivered to the designated user bypassing the antivirus/antispam tools. To do this, you need to inject the mail into LMTP pipe. You may do this using ‘zmlmtpinject’ command as following:

$ zmlmtpinject -r sam@yourhostname.com -s admin@yourhostname.com 281-1216.msg

Remember, to change same@yourhostname.com to the original recipient. admin@yourhostname.com would be the newly rewritten sender for this mail delivery and ‘281-1216.msg’ is the file name of the original email that you found out from the grep command. You can do lmtp injections for one email mail with each command. So, you would require to do this for each emails.

Troubleshooting: Imunify360 database is corrupt. Application cannot run with corrupt database

Error Message:

# service imunify360 start
Starting imunify360: WARNING [+ 3743ms] defence360agent.utils.check_db|DatabaseError detected: database disk image is malformed
WARNING [+ 3766ms] defence360agent.cli.subparsers.common.server|Imunify360 database is corrupt. Application cannot run with corrupt database. Please, contact Imunify360 support team at https://cloudlinux.zendesk.com

Detail Information & Explanation:

If you are using imunify360, an application firewall for linux servers by Cloudlinux team, you might incur an error where it says the database is corrupt. You might first see ‘Imunify360 is not started’ error from the WHM panel and end up getting the above error message as stated. Imunify360 uses a SQL database, located under ‘/var/imunify360/imunify360.db’. This image is checked everytime Imunfi360 tries to start, and if the database is malformed, it would not start. Fortunately, imunify360 comes with tools to handle this database and recover if corrupted.

How to Fix:

First, we start by running database integrity check. This can be done using the following:

imunfiy360-agent checkdb

(From Imunify360 Doc: checkdb  – Check database integrity)

Once done, you can now use ‘migratedb’ to repair and restore if the database is corrupted.

imunify360-agent migratedb

(From Imunify360 Doc: migratedb – Check and repair database if it is corrupted.)

If migratedb fails, the only way to recover this is to reinstall imunify360.

Linux: Disable On-Access Scanning on Sophos AV

We use Sophos AV instead of ClamAV in couple of our linux servers. Sophos comes with on access scanning that uses a kernel module to trigger which file has been accessed unlike ClamAV which only come with signature and a basic scanning tool by default. It has it’s own benefit while drawbacks too. You have to give a certain amount of resources for Sophos. There are times, when you may require to disable the On Access Scanning on Sophos AV to diagnose different issues with the server.

To disable on access scanning on sophos AV, run the following from your terminal/ssh console:

/opt/sophos-av/bin/savdctl disable

To re-enable on access scanning on sophos AV, run the following:

/opt/sophos-av/bin/savdctl enable

Sophos log file is located here:

/opt/sophos-av/log

Sophos comes with multiple control binaries. They can be found at the following directory:

/opt/sophos-av/bin

You can find sophos binaries available at the man page too:

man savdctl