We are using UTM as our mail gateway, lately, a lot of our users have received spoofing emails that appear from themself.
We use emailspooftest dotcom site to test our mail servers, and it detects the problem was
Internal authentication is not enforced.Fix: On inbound email gateways, only allow specific IP addresses to send mail from internal domains or force an auth challenge for internal domains. This is typically a relay setting.
Could anyone suggest how to fix this problem in Sophos?
Hi,
I recommend setting SPF-records for your domain and enabling "Perfom SPF check" in SMTP->Antispam.
bye Josef
BERGMANN engineering & consulting GmbH, Wien/Austria
Hi Josef, thank you for your reply.
SPF is always enabled and records are update-to-date, this seems to be an open relay problem in UTM.
just send an email from an external source as postmaster@yourdomain through the firewall and you have your open relay... no checks at all will be applied...
Which result do you see for the mail from supertool@mxtoolboxsmtpdiag.com to test@mxtoolboxsmtpdiag.com ?
Dirk
Systema Gesellschaft für angewandte Datentechnik mbH // Sophos Platinum PartnerSophos Solution Partner since 2003 If a post solves your question, click the 'Verify Answer' link at this post.
maybe you are completely on the wrong track, I don't think that there is a open relay problem in the UTM.
What was your problem:
Johnny Long said:lot of our users have received spoofing emails that appear from themself
How exactly look this emails? Are the spoofed senders email-addresses maybe only in the body and not in the envelope FROM. Check the SMTP Log in the Mail Manager, what exactly is the from address here.
If these from-domain is your domain, then check your SPF-domainsettings in your DNS.
This is the email header looks like
Received: from EX2016-MDB-C.MYDOMAIN.Hosted (10.2.4.212) by EX2016-MDB-C.MYDOMAIN.Hosted (10.2.4.212) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8 via Mailbox Transport; Wed, 4 May 2022 04:16:58 +1000 Received: from EX2016-MDB-AN.MYDOMAIN.Hosted (10.2.2.129) by EX2016-MDB-C.MYDOMAIN.Hosted (10.2.4.212) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Wed, 4 May 2022 04:16:58 +1000 Received: from ip-1xxxxxxxx-2.compute.internal (10.2.6.109) by EX2016-MDB-AN.MYDOMAIN.Hosted (10.2.2.129) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2308.8 via Frontend Transport; Wed, 4 May 2022 04:17:40 +1000 Received: from [10.2.6.120] (helo=mail.MYDOMAIN.net) by ip-1xxxxxxxx-2.compute.internal with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.90_1) (envelope-from <lxxxxx@xxxxx.com>) id 1nlx5g-0003dL-JJ for lxxxxx@xxxxx.com; Wed, 04 May 2022 04:17:40 +1000 Received: from mail.ghfhgdg.com ([85.239.34.13]:33068) by mail.MYDOMAIN.net with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from <lxxxxx@xxxxx.com>) id 1nlx5X-00057p-2m for lxxxxx@xxxxx.com; Wed, 04 May 2022 04:17:32 +1000 Received: from ip63.ip-51-91-202.eu ([51.91.202.63]:53416 helo=galsan.com) by mail.ghfhgdg.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from <lxxxxx@xxxxx.com>) id 1nlx5V-0007v8-Vs for lxxxxx@xxxxx.com; Tue, 03 May 2022 21:17:28 +0300 X-SASI-Hits: BODYTEXTH_SIZE_3000_MORE 0.000000, BODYTEXTP_SIZE_3000_LESS 0.000000, BODYTEXTP_SIZE_400_LESS 0.000000, BODY_SIZE_10000_PLUS 0.000000, BODY_SIZE_25K_PLUS 0.000000, EXCESSIVE_SUBDOMAINS7 3.000000, FRAUD_ATTACH 0.050000, FROM_NAME_ALLCAPS 0.100000, FROM_RCPT_DOMAIN_NOT_IN_RCVD 0.000000, FROM_SAME_AS_TO_DOMAIN 0.000000, HTML_90_100 0.100000, HTML_95_100 0.100000, IMGSPAM_TABLE_1 0.000000, NO_FUR_HEADER 0.000000, NO_URI_HTTPS 0.000000, OUTBOUND 0.000000, OUTBOUND_SOPHOS 0.000000, SENDER_NO_AUTH 0.000000, SINGLE_HREF_URI_IN_BODY 0.000000, SINGLE_HREF_URI_WITH_EMAIL 0.000000, __ANY_URI 0.000000, __ATTACHMENT_PHRASE 0.000000, __BODY_NO_MAILTO 0.000000, __BULK_NEGATE 0.000000, __CSHC_NS_B_FN_FA 0.000000, __CT 0.000000, __CTYPE_HAS_BOUNDARY 0.000000, __CTYPE_MULTIPART 0.000000, __CTYPE_MULTIPART_ALT 0.000000, __DATA_URL_SCHEME 0.000000, __DATE_TZ_HK 0.000000, __DQ_NEG_DOMAIN 0.000000, __DQ_NEG_HEUR 0.000000, __DQ_NEG_IP 0.000000, __EXCESSIVE_SUBDOMAINS6 0.000000, __EXCESSIVE_SUBDOMAINS7 0.000000, __FAX_BODY 0.000000, __FILESHARE_PHRASE 0.000000, __FRAUD_ANTIABUSE 0.000000, __FROM_DOMAIN_IN_ANY_TO1 0.000000, __FROM_DOMAIN_IN_RCPT 0.000000, __FROM_NAME_NOT_IN_ADDR 0.000000, __FROM_NAME_NOT_IN_BODY 0.000000, __FUR_RDNS_SOPHOS 0.000000, __HAS_FROM 0.000000, __HAS_HTML 0.000000, __HAS_MSGID 0.000000, __HTML_AHREF_TAG 0.000000, __HTML_BAD_END 0.000000, __HTML_TAG_CENTER 0.000000, __HTML_TAG_IMG_X2 0.000000, __HTML_TAG_TABLE 0.000000, __IMGSPAM_TABLE_1 0.000000, __IMG_THEN_TEXT 0.000000, __MIME_HTML 0.000000, __MIME_TEXT_H 0.000000, __MIME_TEXT_H1 0.000000, __MIME_TEXT_H2 0.000000, __MIME_TEXT_P 0.000000, __MIME_TEXT_P1 0.000000, __MIME_TEXT_P2 0.000000, __MIME_VERSION 0.000000, __MULTIPLE_URI_TEXT 0.000000, __OUTBOUND_SOPHOS_FUR 0.000000, __OUTBOUND_SOPHOS_FUR_IP 0.000000, __OUTBOUND_SOPHOS_FUR_RDNS 0.000000, __PHISH_PHRASE10_D 0.000000, __RCPT_DOMAIN_IS_FROM_DOMAIN 0.000000, __SANE_MSGID 0.000000, __SUBJ_ALPHA_END 0.000000, __TAG_EXISTS_HTML 0.000000, __TO_DOMAIN_IN_FROM 0.000000, __TO_DOMAIN_IN_MSGID 0.000000, __TO_MALFORMED_2 0.000000, __TO_NO_NAME 0.000000, __URI_EMAIL_IN_QUERY 0.000000, __URI_IN_BODY 0.000000, __URI_MAILTO 0.000000, __URI_NOT_IMG 0.000000, __URI_NO_PATH 0.000000, __URI_NO_WWW 0.000000, __URI_NS 0.000000, __URI_WITHOUT_PATH 0.000000 X-SASI-Probability: 30% X-SASI-RCODE: 200 X-SASI-Version: Antispam-Engine: 4.1.4, AntispamData: 2022.5.3.173622 From: HOA ORDERS <lxxxxx@xxxxx.com> To: <lxxxxx@xxxxx.com> Subject: Requested HOA Letter Date: Wed, 4 May 2022 02:17:27 +0800 Message-ID: <20220504021727.BFD45D6D250BF3FA@xxxxx.com> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_1F95ED89.02DDA1DF" X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - mail.ghfhgdg.com X-AntiAbuse: Original Domain - xxxxx.com X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - xxxxx.com X-Get-Message-Sender-Via: mail.ghfhgdg.com: authenticated_id: dennis@ghfhgdg.com X-Authenticated-Sender: mail.ghfhgdg.com: dennis@ghfhgdg.com X-Source: X-Source-Args: X-Source-Dir: Return-Path: lxxxxx@xxxxx.com X-MS-Exchange-Organization-Network-Message-Id: 2be4961d-c269-4b3a-e3f4-08da2d3135da X-MS-Exchange-Organization-AVStamp-Enterprise: 1.0 X-MS-Exchange-Organization-AuthSource: EX2016-MDB-AN.MYDOMAIN.Hosted X-MS-Exchange-Organization-AuthAs: Anonymous X-MS-Exchange-Processed-By-BccFoldering: 15.01.2308.008
Ok, I suggest xxxxx.com stands for your domain.
Which hop is your UTM? mail.MYDOMAIN.net?
How looks your SPF-Setting in the DNS?
Yes, mail.MYDOMAIN.net is the UTM hop.
This is what the SPF settings look like:v=spf1 mx ip4:13.xx.xx.xx ip4:13.xx.xx.xx ip4:13.xx.xx.xx ip4:13.xx.xx.xx ip4:13.xx.xx.xx include:spf.messagelabs.com include:spf.protection.outlook.com include:spf.smtp2go.com ~all
Can anyone spot any issues?
The results show as
SendSMTPCommand: You hung up on us after we connected. Please whitelist us. (connection lost)
Ok so you use "Softfail" (~all) in your SPF-policy, these will not stop the spoofed mail on the UTM.
More details see here Sophos UTM: Enable Sender Policy Framework (SPF)
"... Your SPF record should contain the token "-all" at the end not "~all". This is a common reason why people are not rejecting spoofed mail as expected."
Hi Josef, I know we use "Softfail", but we have "Perform SPF check" turned on and I can see a lot of emails got rejected because of SPF check failed.
I still think we have is an open relay problem, not an SPF problem.
If you don't check your own mail logs after doing the OpenRelay test, you would never really know this.
PS: and i think SPF soft-fail will pass UTM-Spam filter. (you may check SPF-records from SPF-blocked mails)