Fake email quarantine notification
Detects phishing messages implying that emails have been delayed or blocked, prompting users to view, release, or delete pending messages.
Sublime rule (View on GitHub)
1name: "Fake email quarantine notification"
2description: "Detects phishing messages implying that emails have been delayed or blocked, prompting users to view, release, or delete pending messages."
3type: "rule"
4severity: "high"
5source: |
6 type.inbound
7
8 and length(body.links) < 10
9 and (
10 any(ml.nlu_classifier(body.current_thread.text).intents,
11 .name == "cred_theft" and .confidence == "high"
12 )
13 or (
14 length(body.current_thread.text) < 250
15 and any(recipients.to,
16 strings.icontains(body.current_thread.text, .email.domain.sld)
17 or strings.icontains(body.current_thread.text, .email.local_part)
18 )
19 )
20 )
21 and (
22 3 of (
23 strings.ilike(body.current_thread.text, "*review*"),
24 strings.ilike(body.current_thread.text, "*release*"),
25 strings.ilike(body.current_thread.text, "*quaratine*"),
26 strings.ilike(body.current_thread.text, "*messages*"),
27 strings.ilike(body.current_thread.text, "*blocked*"),
28 strings.ilike(body.current_thread.text, "*notification*"),
29 strings.ilike(body.current_thread.text, "*kindly*"),
30 strings.ilike(body.current_thread.text, "*on hold*"),
31 strings.ilike(body.current_thread.text, "*pending*")
32 )
33 )
34 and (
35 any(body.links,
36 regex.icontains(.display_text, "view", "release", "messages", "delete")
37 )
38 or (
39 length(body.links) < 3
40 and any(body.links,
41 any(recipients.to,
42 .email.domain.root_domain == ..display_url.domain.root_domain
43 and ..mismatched
44 )
45 )
46 )
47 )
48 and not any(body.links,
49 regex.icontains(.display_text, "view document")
50 )
51 and sender.email.domain.root_domain not in (
52 "bing.com",
53 "microsoft.com",
54 "microsoftonline.com",
55 "microsoftsupport.com",
56 "microsoft365.com",
57 "office.com",
58 "onedrive.com",
59 "sharepointonline.com",
60 "yammer.com",
61 )
62
63 // negate org domains unless they fail DMARC authentication
64 and (
65 (
66 sender.email.domain.root_domain in $org_domains
67 and not headers.auth_summary.dmarc.pass
68 )
69 or sender.email.domain.root_domain not in $org_domains
70 )
71
72 // negate highly trusted sender domains unless they fail DMARC authentication
73 and (
74 (
75 sender.email.domain.root_domain in $high_trust_sender_root_domains
76 and not headers.auth_summary.dmarc.pass
77 )
78 or sender.email.domain.root_domain not in $high_trust_sender_root_domains
79 )
80 and not profile.by_sender().solicited
81 and not profile.by_sender().any_false_positives
82
83attack_types:
84 - "Credential Phishing"
85tactics_and_techniques:
86 - "Social engineering"
87detection_methods:
88 - "Content analysis"
89 - "Natural Language Understanding"
90 - "Sender analysis"
91id: "73f26a3d-b7a5-5b85-83e6-45f1b40f78fb"