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public:emai:malware [2023-03-09 09:41] – vesely | public:emai:malware [2023-03-09 09:43] – [Monitoring and filtering agenda] vesely |
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* [[:public:emai:malware#spf_hard_fail|SPF hard fail]] - sending server __is not on the allowed list__ provided by domain's owner and the domain owner asks for message blocking. | * [[:public:emai:malware#spf_hard_fail|SPF hard fail]] - sending server __is not on the allowed list__ provided by domain's owner and the domain owner asks for message blocking. |
* [[:public:emai:malware#spf_soft_fail|SPF soft fail]] - | * [[:public:emai:malware#spf_soft_fail|SPF soft fail]] - <font inherit/inherit;;#f39c12;;inherit>[Suspicious - SPF - soft fail]</font> - sending server is not listed among allowed ones, but the domain owner allow message passing with warning. |
<font inherit/inherit;;#f39c12;;inherit>[Suspicious - SPF - soft fail]</font> - sending server is not listed among allowed ones, but the domain owner allow message passing with warning. | * [[:public:emai:malware#spf_bad_alignment|SPF bad alignment]] - <font inherit/inherit;;#f39c12;;inherit>[Covert sender]</font> - verify the authenticity of the domain sending the email by using two diffrenent header signatures in the message. |
* [[:public:emai:malware#spf_bad_alignment|SPF bad alignment]] - | * [[:public:emai:malware#bad_dmarc|Bad DMARC]] - <font inherit/inherit;;#f39c12;;inherit>[Bad DMARC]</font> - the sender's domain does not have DMARC record and SPF set properly. |
<font inherit/inherit;;#f39c12;;inherit>[Covert sender]</font> - verify the authenticity of the domain sending the email by using two diffrenent header signatures in the message. | * [[:public:emai:malware#bad_dmarc|Bad ARC]] - <font inherit/inherit;;#f39c12;;inherit>[Suspicious - bad ARC]</font> - the sender's email has ARC Seal but it's validation did not succed (e.g. invalid calculated email hash). |
* [[:public:emai:malware#bad_dmarc|Bad DMARC]] - | * [[:public:emai:malware#ip_reputation_database_-_dnsbl|DNSBL listed]] - <font inherit/inherit;;#f39c12;;inherit>[IP reputation - DNSBL listed]</font> - the sender's IP is listed in SPAM database. |
<font inherit/inherit;;#f39c12;;inherit>[Bad DMARC]</font> - the sender's domain does not have DMARC record and SPF set properly. | * [[:public:emai:malware#suspicious_newsletter|Suspicious Newsletter]] - <font inherit/inherit;;#f39c12;;inherit>[Newsletter]</font> - it may be found that certain newsletters are suspicious because they may actually be spam under the disguise of newsletters. |
* [[:public:emai:malware#bad_dmarc|Bad ARC]] - | * [[:public:emai:malware#ip_reputation|Bad IP reputation]] - <font inherit/inherit;;#f39c12;;inherit>[IP reputaton]</font> - emails from IP addresses with bad reputation may be discarded or quarantined. It may be dangerous to receive emails from such IPs. |
<font inherit/inherit;;#f39c12;;inherit>[Suspicious - bad ARC]</font> - the sender's email has ARC Seal but it's validation did not succed (e.g. invalid calculated email hash). | * [[:public:emai:malware#warning_disclaimer_prepended_to_email|Warning Disclaimer]] (prepended to email) - <font inherit/inherit;;#f39c12;;inherit>[Newsletter]</font> - Anti-Phishing engine cannot decide about targeting URL link (usually concealed by click spying) |
* [[:public:emai:malware#ip_reputation_database_-_dnsbl|DNSBL listed]] - | |
<font inherit/inherit;;#f39c12;;inherit>[IP reputation - DNSBL listed]</font> - the sender's IP is listed in SPAM database. | |
* [[:public:emai:malware#suspicious_newsletter|Suspicious Newsletter]] - | |
<font inherit/inherit;;#f39c12;;inherit>[Newsletter]</font> - it may be found that certain newsletters are suspicious because they may actually be spam under the disguise of newsletters. | |
* [[:public:emai:malware#ip_reputation|Bad IP reputation]] - | |
<font inherit/inherit;;#f39c12;;inherit>[IP reputaton]</font> - emails from IP addresses with bad reputation may be discarded or quarantined. It may be dangerous to receive emails from such IPs. | |
* [[:public:emai:malware#warning_disclaimer_prepended_to_email|Warning Disclaimer]] (prepended to email) - | |
<font inherit/inherit;;#f39c12;;inherit>[Newsletter]</font> - Anti-Phishing engine cannot decide about targeting URL link (usually concealed by click spying) | |
* [[:public:emai:malware#pdf_macro|PDF macro]] - PDF files include the ability to execute code on your device — and that’s where the danger lies | * [[:public:emai:malware#pdf_macro|PDF macro]] - PDF files include the ability to execute code on your device — and that’s where the danger lies |
* [[:public:emai:malware#suspicious_content_html_links_docs_macro|Suspicious content]] (HTML links, docs) - | * [[:public:emai:malware#suspicious_content_html_links_docs_macro|Suspicious content]] (HTML links, docs) - <font inherit/inherit;;#f39c12;;inherit>[Suspicious]</font> - HTML content and attachments may contain potentially hazardous tags and attributes |
<font inherit/inherit;;#f39c12;;inherit>[Suspicious]</font> - HTML content and attachments may contain potentially hazardous tags and attributes | * [[:public:emai:malware#image_spam|Image Spam]] (images, pdf) - <font inherit/inherit;;#f39c12;;inherit>[Image spam]</font> - Some spammers conceal spam text as an image or PDF document. |
* [[:public:emai:malware#image_spam|Image Spam]] (images, pdf) - | * [[:public:emai:malware#deepheader_analysis|Deepheader analysis]] - <font inherit/inherit;;#f39c12;;inherit>[Suspicious - header analysis]</font> - Deepheader analysis examines the entire message header for spam characteristics. |
<font inherit/inherit;;#f39c12;;inherit>[Image spam]</font> - Some spammers conceal spam text as an image or PDF document. | |
* [[:public:emai:malware#deepheader_analysis|Deepheader analysis]] - | |
<font inherit/inherit;;#f39c12;;inherit>[Suspicious - header analysis]</font> - Deepheader analysis examines the entire message header for spam characteristics. | |
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===== Possible Spoof ===== | ===== Possible Spoof ===== |
**Example of spoof email:** | **Example of spoof email:** |
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MAIL FROM: **johndoe2 <font inherit/inherit;;#2980b9;;inherit>@gmail.com</font> ** \\ | MAIL FROM: **johndoe2 |
From: **john.doe <font inherit/inherit;;#d35400;;inherit>@cerge-ei.cz</font> ** \\ | <font inherit/inherit;;#2980b9;;inherit>@gmail.com</font> ** \\ |
To: **jane.dow <font inherit/inherit;;#d35400;;inherit>@cerge-ei.cz</font> ** | From: **john.doe |
| <font inherit/inherit;;#d35400;;inherit>@cerge-ei.cz</font> ** \\ |
| To: **jane.dow |
| <font inherit/inherit;;#d35400;;inherit>@cerge-ei.cz</font> ** |
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Such email is suspicious. Some user with an account at Gmail (johndoe2@gmail.com) set his profile to use institutional email address (john.doe@cerge-ei.cz). \\ | Such email is suspicious. Some user with an account at Gmail (johndoe2@gmail.com) set his profile to use institutional email address (john.doe@cerge-ei.cz). \\ |
</code> | </code> |
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https://en.wikipedia.org/wiki/Authenticated_Received_Chain | [[https://en.wikipedia.org/wiki/Authenticated_Received_Chain|https://en.wikipedia.org/wiki/Authenticated_Received_Chain]] |
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https://dmarc.org/presentations/ARC-Overview-2016Q3-v01.pdf | [[https://dmarc.org/presentations/ARC-Overview-2016Q3-v01.pdf|https://dmarc.org/presentations/ARC-Overview-2016Q3-v01.pdf]] |
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===== Reputation databases - Blacklists ===== | ===== Reputation databases - Blacklists ===== |
Certain sort of newsletter senders wants to track recipients clicks (to monetize and/or monitor recipient behavior) so they conceal the target URL behind their own hash. It is then undecidable whether the redirected URL is OK or not (phishing). | Certain sort of newsletter senders wants to track recipients clicks (to monetize and/or monitor recipient behavior) so they conceal the target URL behind their own hash. It is then undecidable whether the redirected URL is OK or not (phishing). |
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**Example** | **Example** <font inherit/inherit;;#c0392b;;inherit>**Obfuscated/unresolvable link**:</font> If you get the newsletter from **bostonglobe.com** with links in the form [[https://bostonglobe.us11|https://bostonglobe.us11]].**list-manage.com/track/click?u=90f9e490a86&id=0c98f5&e=e8fef** , it cannot be said what is the targeting URL. Hence the ** <font inherit/inherit;;#c0392b;;inherit>warning about uncertain content is added</font> **. |
<font inherit/inherit;;#c0392b;;inherit>**Obfuscated/unresolvable link**:</font> If you get the newsletter from **bostonglobe.com** with links in the form [[https://bostonglobe.us11|https://bostonglobe.us11]].**list-manage.com/track/click?u=90f9e490a86&id=0c98f5&e=e8fef** , it cannot be said what is the targeting URL. Hence the ** <font inherit/inherit;;#c0392b;;inherit>warning about uncertain content is added</font> **. | |
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** <font inherit/inherit;;#27ae60;;inherit>Regular/direct link</font> **: If the newsletter from **newyorker.com** contains links in the form [[https://link|https://link]].**newyorker.com/view/5dc1b3fc91f4/03075c2d** , it may be tracked down to the target URL and **is considered safe**. | ** <font inherit/inherit;;#27ae60;;inherit>Regular/direct link</font> **: If the newsletter from **newyorker.com** contains links in the form [[https://link|https://link]].**newyorker.com/view/5dc1b3fc91f4/03075c2d** , it may be tracked down to the target URL and **is considered safe**. |
//Added subject tag: [Suspicious - header analysis]// | //Added subject tag: [Suspicious - header analysis]// |
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//Added warning text: "Deepheader analysis examines header for spam characteristics. Don't click any link unless you are certain it's legitimate.////"// | //Added warning text: "Deepheader analysis examines header for spam characteristics. Don't click any link unless you are certain it's legitimate.////"// <font inherit/inherit;;#c0392b;;inherit>Tool to examine message header (displays human-readable content):</font> [[https://mha.azurewebsites.net/|https://mha.azurewebsites.net/]] |
<font inherit/inherit;;#c0392b;;inherit>Tool to examine message header (displays human-readable content):</font> [[https://mha.azurewebsites.net/|https://mha.azurewebsites.net/]] | |
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Deepheader analysis examines the entire message header for spam characteristics. | Deepheader analysis examines the entire message header for spam characteristics. |