public:emai:malware

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public:emai:malware [2023-03-09 09:41] – veselypublic:emai:malware [2023-03-09 12:13] (current) – vesely
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 **The generously opened and heterogeneous nature of the academic and research institution is extremely vulnerable to such kind of threat.** Regular enterprises and other profit-making businesses are usually much more homogenous with much simpler rules and measures against the third parties (no IMAP, no access to emails from non-business devices, strict mobile device management, blocked or limited traffic etc.). **The generously opened and heterogeneous nature of the academic and research institution is extremely vulnerable to such kind of threat.** Regular enterprises and other profit-making businesses are usually much more homogenous with much simpler rules and measures against the third parties (no IMAP, no access to emails from non-business devices, strict mobile device management, blocked or limited traffic etc.).
  
-Both areas of malicious or potentially problematic emails and regular emails are overlapping; it is not easy to distinguish between them sometimes.+ 
 +<font inherit/inherit;;#f39c12;;inherit>**Both areas**</font>  of 
 + <font inherit/inherit;;#c0392b;;inherit>**malicious or potentially problematic emails**</font>  and 
 + <font inherit/inherit;;#339933;;inherit>**regular emails**</font>  ** <font inherit/inherit;;#f39c12;;inherit>are overlapping</font> **; it is not easy to distinguish between them sometimes. 
  
 **The most dangerous threats are usually those of the "zero day attack" nature**; they usually take advantage of badly protected or misprotected email servers and domains so they can mimic the regular sender.\\ **The most dangerous threats are usually those of the "zero day attack" nature**; they usually take advantage of badly protected or misprotected email servers and domains so they can mimic the regular sender.\\
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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#arc|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.+
  
 ===== Possible Spoof ===== ===== Possible Spoof =====
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 **Example of spoof email:** **Example of spoof email:**
  
-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> **
  
 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). \\
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 </code> </code>
  
-https://en.wikipedia.org/wiki/Authenticated_Received_Chain+[[https://en.wikipedia.org/wiki/Authenticated_Received_Chain|https://en.wikipedia.org/wiki/Authenticated_Received_Chain]]
  
-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]]
  
 ===== Reputation databases - Blacklists ===== ===== Reputation databases - Blacklists =====
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 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).
  
-**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> **.+
  
 ** <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**.
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 //Added subject tag: [Suspicious - header analysis]// //Added subject tag: [Suspicious - header analysis]//
  
-//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/]]+
  
 Deepheader analysis examines the entire message header for spam characteristics. Deepheader analysis examines the entire message header for spam characteristics.
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