Detection rules › Sublime MQL

Brand impersonation: Evite

Severity
medium
Type
rule
Source
github.com/sublime-security/sublime-rules

Detects messages impersonating Evite invitations by looking for invitation language while not originating from legitimate Evite domains.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesImpersonation: Brand, Social engineering

Event coverage

Rule body MQL

type.inbound
and strings.contains(body.html.raw, 'evitecdn.com')
and length(filter(html.xpath(body.html, '//img/@src').nodes,
                  // calling parse_url allows url decoding to help us
                  strings.parse_url(.raw).domain.root_domain == 'evitecdn.com'
           )
) >= 2
and length(filter(body.links,
                  .href_url.domain.root_domain == "evite.com"
                  and regex.contains(.href_url.path, '^/_ct/[a-f0-9]{40}/')
           )
) < 3
and not (
  (subject.is_forward or subject.is_reply)
  and (length(headers.references) != 0 or headers.in_reply_to is not null)
  and length(body.previous_threads) > 0
)
and not (
  sender.email.domain.root_domain == "evite.com"
  and headers.auth_summary.dmarc.pass
)

Detection logic

Scope: inbound message.

Detects messages impersonating Evite invitations by looking for invitation language while not originating from legitimate Evite domains.

  1. inbound message
  2. body.html.raw contains 'evitecdn.com'
  3. length(filter(html.xpath(body.html, '//img/@src').nodes, strings.parse_url(.raw).domain.root_domain == 'evitecdn.com')) ≥ 2
  4. length(filter(body.links, .href_url.domain.root_domain == 'evite.com' and regex.contains(.href_url.path, '^/_ct/[a-f0-9]{40}/'))) < 3
  5. not:
    • all of:
      • any of:
        • subject.is_forward
        • subject.is_reply
      • any of:
        • length(headers.references) is not 0
        • headers.in_reply_to is set
      • length(body.previous_threads) > 0
  6. not:
    • all of:
      • sender.email.domain.root_domain is 'evite.com'
      • headers.auth_summary.dmarc.pass

Inspects: body.html, body.html.raw, body.links, body.links[].href_url.domain.root_domain, body.links[].href_url.path, body.previous_threads, headers.auth_summary.dmarc.pass, headers.in_reply_to, headers.references, sender.email.domain.root_domain, subject.is_forward, subject.is_reply, type.inbound. Sensors: html.xpath, regex.contains, strings.contains, strings.parse_url.

Indicators matched (4)

FieldMatchValue
strings.containssubstringevitecdn.com
body.links[].href_url.domain.root_domainequalsevite.com
regex.containsregex^/_ct/[a-f0-9]{40}/
sender.email.domain.root_domainequalsevite.com