Attachment: HTML Smuggling Microsoft Sign In
Scans HTML files to detect HTML smuggling techniques impersonating a Microsoft login page.
Sublime rule (View on GitHub)
1name: "Attachment: HTML Smuggling Microsoft Sign In"
2description: |
3 Scans HTML files to detect HTML smuggling techniques impersonating a Microsoft login page.
4type: "rule"
5severity: "high"
6source: |
7 type.inbound
8 and any(attachments,
9 (
10 .file_extension in~ ("html", "htm", "shtml", "dhtml")
11 or .file_extension in~ $file_extensions_common_archives
12 or .file_type == "html"
13 )
14 and any(file.explode(.),
15 .scan.entropy.entropy >= 5.7
16 and .flavors.mime == "text/html"
17 and length(.scan.javascript.identifiers) == 0
18 and any(.scan.url.urls,
19 .domain.domain not in $tranco_1m
20 or .domain.root_domain in $free_subdomain_hosts
21 )
22
23 // seen in the wild: "sign in to your account", "sign in to your microsoft account"
24 and strings.ilike(.scan.html.title, "*sign in*", "*microsoft*")
25 )
26 )
27 and (
28 not profile.by_sender().solicited
29 or (
30 profile.by_sender().any_messages_malicious_or_spam
31 and not profile.by_sender().any_false_positives
32 )
33 )
34 // allow Microsoft domains just to be safe
35 and sender.email.domain.root_domain not in~ ('microsoft.com', 'microsoftsupport.com', 'office.com')
36attack_types:
37 - "Credential Phishing"
38tactics_and_techniques:
39 - "Free subdomain host"
40 - "HTML smuggling"
41 - "Impersonation: Brand"
42 - "Social engineering"
43detection_methods:
44 - "Archive analysis"
45 - "Content analysis"
46 - "File analysis"
47 - "Header analysis"
48 - "Javascript analysis"
49 - "Sender analysis"
50 - "URL analysis"
51id: "878d6385-95c2-5540-a887-a6fa9456409c"