Detection rules › Sublime MQL

Open redirect: City of Calgary

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

Message contains use of calgary.ca's open redirect but the sender is not the City of Calgary.

Threat classification

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

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesExploit, Open redirect, Social engineering

Event coverage

Rule body MQL

type.inbound
and any(body.links,
        .href_url.domain.root_domain == 'calgary.ca'
        and .href_url.path =~ '/_layouts/cocis/DirectDownload.aspx'
        and strings.icontains(.href_url.query_params, "redirect")
)
and sender.email.domain.root_domain != 'calgary.ca'

// negate highly trusted sender domains unless they fail DMARC authentication
and (
  (
    sender.email.domain.root_domain in $high_trust_sender_root_domains
    and not headers.auth_summary.dmarc.pass
  )
  or sender.email.domain.root_domain not in $high_trust_sender_root_domains
)

Detection logic

Scope: inbound message.

Message contains use of calgary.ca's open redirect but the sender is not the City of Calgary.

  1. inbound message
  2. any of body.links where all hold:
    • .href_url.domain.root_domain is 'calgary.ca'
    • .href_url.path is '/_layouts/cocis/DirectDownload.aspx'
    • .href_url.query_params contains 'redirect'
  3. sender.email.domain.root_domain is not 'calgary.ca'
  4. any of:
    • all of:
      • sender.email.domain.root_domain in $high_trust_sender_root_domains
      • not:
        • headers.auth_summary.dmarc.pass
    • sender.email.domain.root_domain not in $high_trust_sender_root_domains

Inspects: body.links, body.links[].href_url.domain.root_domain, body.links[].href_url.path, body.links[].href_url.query_params, headers.auth_summary.dmarc.pass, sender.email.domain.root_domain, type.inbound. Sensors: strings.icontains. Reference lists: $high_trust_sender_root_domains.

Indicators matched (3)

FieldMatchValue
body.links[].href_url.domain.root_domainequalscalgary.ca
body.links[].href_url.pathequals/_layouts/cocis/DirectDownload.aspx
strings.icontainssubstringredirect