Detection rules › Sublime MQL

Open redirect: buildingengines.com

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

Detects messages containing buildingengines.com redirect links that use the _redirectTo parameter to redirect users to malicious sites. This has been observed in phishing campaigns.

Threat classification

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

CategoryValues
Attack typesCredential Phishing, Malware/Ransomware
Tactics and techniquesOpen redirect

Event coverage

Rule body MQL

type.inbound
and any(body.links,
        // Look for buildingengines URLs
        .href_url.domain.domain == "app.buildingengines.com"
        and strings.icontains(.href_url.query_params, '_redirectTo=')
        // Make sure it's not redirecting back to buildingengines.com
        and not regex.icontains(.href_url.query_params,
                                '_redirectTo=(?:https?(?:%3a|:))?(?:%2f|\/){2}[^&]*buildingengines\.com(?:\&|\/|$|%2f)'
        )
)
// Exclude legitimate Building Engines domains as senders
and not sender.email.domain.root_domain == "buildingengines.com"

// 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.

Detects messages containing buildingengines.com redirect links that use the _redirectTo parameter to redirect users to malicious sites. This has been observed in phishing campaigns.

  1. inbound message
  2. any of body.links where all hold:
    • .href_url.domain.domain is 'app.buildingengines.com'
    • .href_url.query_params contains '_redirectTo='
    • not:
      • .href_url.query_params matches '_redirectTo=(?:https?(?:%3a|:))?(?:%2f|\\/){2}[^&]*buildingengines\\.com(?:\\&|\\/|$|%2f)'
  3. not:
    • sender.email.domain.root_domain is 'buildingengines.com'
  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.domain, body.links[].href_url.query_params, headers.auth_summary.dmarc.pass, sender.email.domain.root_domain, type.inbound. Sensors: regex.icontains, strings.icontains. Reference lists: $high_trust_sender_root_domains.

Indicators matched (4)

FieldMatchValue
body.links[].href_url.domain.domainequalsapp.buildingengines.com
strings.icontainssubstring_redirectTo=
regex.icontainsregex_redirectTo=(?:https?(?:%3a|:))?(?:%2f|\/){2}[^&]*buildingengines\.com(?:\&|\/|$|%2f)
sender.email.domain.root_domainequalsbuildingengines.com