Brand impersonation: OpenAI with payment issues

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

Detects messages impersonating OpenAI or ChatGPT with payment-related content such as subscription cancellation, payment failures, or billing updates from non-OpenAI domains.

Threat classification

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

Category	Values
Attack types	Credential Phishing
Tactics and techniques	Impersonation: Brand, Social engineering

Event coverage

Message attribute
body.current_thread
headers.auth_summary
sender
sender.email
subject
type

Rule body MQL

type.inbound
and (
  // sender or subject contains openai or chatgpt
  regex.icontains(sender.display_name, '\bchat\s*gpt\b')
  or regex.icontains(sender.display_name, '\bopen\s*a[li]\b')
  or regex.icontains(subject.subject, '\bchat\s*gpt\b')
  or regex.icontains(subject.subject, '\bopen\s*a[li]\b')
  or regex.icontains(body.current_thread.text,
                     '(?:regarding\s*your\s*Open\s*A[lI]\s*account|Open\s*A[lI]\s*\.\s*All\s*rights\s*reserved|the\s*open\s*ai\s*team)'
  )
)
and 2 of (
  // payment phrase
  regex.icontains(body.current_thread.text,
                  'update (?:payment method|your (?:billing|payment))'
  ),
  regex.icontains(body.current_thread.text,
                  'Subscription (?:has expired|(?:will be)?Cancel+ed)'
  ),
  regex.icontains(body.current_thread.text,
                  'issue with (?:the transaction|payment)'
  ),
  regex.icontains(body.current_thread.text, "you(?:'ll| will) lose access"),
  regex.icontains(body.current_thread.text,
                  'payment (?:is not successful|error|was declined)'
  ),
  regex.icontains(body.current_thread.text,
                  'unable to (?:process|automatically charge)'
  ),
  strings.icontains(body.current_thread.text, 'bank or card issuer'),
  strings.icontains(body.current_thread.text, 'issue with the transaction'),
  strings.icontains(body.current_thread.text, 'could not be processed'),
  strings.icontains(body.current_thread.text, 'settle the outstanding'),
  strings.icontains(body.current_thread.text, 'account will be downgraded'),
  strings.icontains(body.current_thread.text, 'Renew Subscription'),
  strings.icontains(body.current_thread.text, 'balance is settled'),
  strings.icontains(body.current_thread.text, 'will renew automatically'),
  strings.icontains(body.current_thread.text, 'process your payment'),
  strings.icontains(body.current_thread.text, 'keep your subscription active'),
  strings.icontains(body.current_thread.text, 'avoid any interruption'),
  strings.icontains(body.current_thread.text, 'charge attempt was unsuccessful'),
  strings.icontains(body.current_thread.text, 'scheduled for cancellation'),
  strings.icontains(body.current_thread.text, 'authorizing your payment'),
  strings.icontains(body.current_thread.text, 'Declining Payment'),
  strings.icontains(body.current_thread.text, 'Insufficient funds'),
  strings.icontains(body.current_thread.text, 'Card has expired'),
  strings.icontains(body.current_thread.text, 'exceeds your credit limit'),
  strings.icontains(body.current_thread.text, 'plan features have been paused'),
  strings.icontains(body.current_thread.text, 'saved payment method'),
  strings.icontains(body.current_thread.text, 'active without interruption')
)
// not from openai
and not sender.email.domain.root_domain == 'openai.com'
// negate highly trusted sender domains unless they fail DMARC authentication
and not (
  sender.email.domain.root_domain in $high_trust_sender_root_domains
  and coalesce(headers.auth_summary.dmarc.pass, false)
)

Detection logic

Scope: inbound message.

Detects messages impersonating OpenAI or ChatGPT with payment-related content such as subscription cancellation, payment failures, or billing updates from non-OpenAI domains.

inbound message
any of:
- sender.display_name matches '\\bchat\\s*gpt\\b'
- sender.display_name matches '\\bopen\\s*a[li]\\b'
- subject.subject matches '\\bchat\\s*gpt\\b'
- subject.subject matches '\\bopen\\s*a[li]\\b'
- body.current_thread.text matches '(?:regarding\\s*your\\s*Open\\s*A[lI]\\s*account|Open\\s*A[lI]\\s*\\.\\s*All\\s*rights\\s*reserved|the\\s*open\\s*ai\\s*team)'
at least 2 of:
- body.current_thread.text matches 'update (?:payment method|your (?:billing|payment))'
- body.current_thread.text matches 'Subscription (?:has expired|(?:will be)?Cancel+ed)'
- body.current_thread.text matches 'issue with (?:the transaction|payment)'
- body.current_thread.text matches "you(?:'ll| will) lose access"
- body.current_thread.text matches 'payment (?:is not successful|error|was declined)'
- body.current_thread.text matches 'unable to (?:process|automatically charge)'
- body.current_thread.text contains 'bank or card issuer'
- body.current_thread.text contains 'issue with the transaction'
- body.current_thread.text contains 'could not be processed'
- body.current_thread.text contains 'settle the outstanding'
- body.current_thread.text contains 'account will be downgraded'
- body.current_thread.text contains 'Renew Subscription'
- body.current_thread.text contains 'balance is settled'
- body.current_thread.text contains 'will renew automatically'
- body.current_thread.text contains 'process your payment'
- body.current_thread.text contains 'keep your subscription active'
- body.current_thread.text contains 'avoid any interruption'
- body.current_thread.text contains 'charge attempt was unsuccessful'
- body.current_thread.text contains 'scheduled for cancellation'
- body.current_thread.text contains 'authorizing your payment'
- body.current_thread.text contains 'Declining Payment'
- body.current_thread.text contains 'Insufficient funds'
- body.current_thread.text contains 'Card has expired'
- body.current_thread.text contains 'exceeds your credit limit'
- body.current_thread.text contains 'plan features have been paused'
- body.current_thread.text contains 'saved payment method'
- body.current_thread.text contains 'active without interruption'
not:
- sender.email.domain.root_domain is 'openai.com'
not:
- all of:
  - sender.email.domain.root_domain in $high_trust_sender_root_domains
  - coalesce(headers.auth_summary.dmarc.pass)

Inspects: body.current_thread.text, headers.auth_summary.dmarc.pass, sender.display_name, sender.email.domain.root_domain, subject.subject, type.inbound. Sensors: regex.icontains, strings.icontains. Reference lists: $high_trust_sender_root_domains.

Indicators matched (31)

Field	Match	Value
`regex.icontains`	regex	`\bchat\s*gpt\b`
`regex.icontains`	regex	`\bopen\s*a[li]\b`
`regex.icontains`	regex	`(?:regarding\syour\sOpen\sA[lI]\saccount\|Open\sA[lI]\s\.\sAll\srights\sreserved\|the\sopen\sai\steam)`
`regex.icontains`	regex	`update (?:payment method\|your (?:billing\|payment))`
`regex.icontains`	regex	`Subscription (?:has expired\|(?:will be)?Cancel+ed)`
`regex.icontains`	regex	`issue with (?:the transaction\|payment)`
`regex.icontains`	regex	`you(?:'ll\| will) lose access`
`regex.icontains`	regex	`payment (?:is not successful\|error\|was declined)`
`regex.icontains`	regex	`unable to (?:process\|automatically charge)`
`strings.icontains`	substring	`bank or card issuer`
`strings.icontains`	substring	`issue with the transaction`
`strings.icontains`	substring	`could not be processed`

19 more

`strings.icontains`	substring	`settle the outstanding`
`strings.icontains`	substring	`account will be downgraded`
`strings.icontains`	substring	`Renew Subscription`
`strings.icontains`	substring	`balance is settled`
`strings.icontains`	substring	`will renew automatically`
`strings.icontains`	substring	`process your payment`
`strings.icontains`	substring	`keep your subscription active`
`strings.icontains`	substring	`avoid any interruption`
`strings.icontains`	substring	`charge attempt was unsuccessful`
`strings.icontains`	substring	`scheduled for cancellation`
`strings.icontains`	substring	`authorizing your payment`
`strings.icontains`	substring	`Declining Payment`
`strings.icontains`	substring	`Insufficient funds`
`strings.icontains`	substring	`Card has expired`
`strings.icontains`	substring	`exceeds your credit limit`
`strings.icontains`	substring	`plan features have been paused`
`strings.icontains`	substring	`saved payment method`
`strings.icontains`	substring	`active without interruption`
`sender.email.domain.root_domain`	equals	`openai.com`

`j` / `k`	Scroll down / up
`d` / `u`	Half-page down / up
`gg` / `G`	Top / bottom
`h` / `l`	History back / forward
`f`	Follow link (`Shift` = new tab)
`/`	Focus search
`?`	Toggle this help
`↑` / `↓`	Navigate search results
`Enter`	Open highlighted result
`Esc`	Close results / dialog

`type:`	`events` / `rules` / `providers`
`vendor:`	`sigma` / `elastic` / `splunk` / `kusto` / `chronicle` (vendor name alone also works: `sigma:`, `kql:`, `secops:`…)
`tactic:`	TA-id, slug, or name: `credential_access`, `TA0006`
`technique:`	technique or sub-technique ID: `T1003`, `T1003.001` (alias `tech:`)
`severity:`	`critical` / `high` / `medium` / `low` / `informational` (alias `sev:`)
`risk_score`	Numeric comparison on the Elastic risk score (0 to 100): `risk_score>50`, `risk_score<=20`, `risk_score=99` (alias `risk`; Elastic rules only)
`stages:`	Rules with exactly N pipeline stages
`correlation:`	`single_event` / `sequence` / `alternatives` / `alternatives_cross_log` / `all_required` / `correlated`
`with:`	Co-occurrence event-id; stacks (`with:4624 with:4769`) to require all, while a comma list in one occurrence (`with:4624,4769`) is an either-or group. Implies multi-event
`like:`	Structural neighbors of a rule slug (equivalents + subsumption stricter / broader): `like:comsvcs_lsass_memory_dump-splunk-sysmon`
`groupby:`	Entity-grouping substring match against `group_by_keys`: `groupby:user`, `groupby:host`
`uses:`	Rules whose predicate tree touches the field (any kind, any value): `uses:CommandLine`
`excludes:`	Rules with top-level `not()` clauses on the field (FP whitelists): `excludes:ParentImage`
`field:` / `value:`	Predicate search; narrows rule cards to those with a matching leaf and drives the indicator tier. Unquoted = substring, wildcards allowed (`value:mimikatz`)
`indicator:`	Shorthand for `field:F value:V`: `indicator:Image=*\powershell.exe`
`kind:`	Filter by predicate kind. Narrows rule cards to those carrying a matching predicate leaf (`vendor:elastic kind:cidr_match`) and drives the indicator tier: `contains` / `starts_with` / `ends_with` / `regex` / `cidr` / `eq` / `in` … (operator aliases `op:`/`match:`)
`has:` / `no:`	`sample`, `field`, `notes`, `refs`, `trace`, `thirdparty`, `rule`, `pattern`, `timewindow`, `threshold`, `newterms`, `sigma`/`elastic`/`splunk`/`kusto`/`chronicle`
`-op:val`	Exclude matches; works on most operators but not `type:`/`like:`/`has:`/`no:` (use `no:<flag>` to exclude a rule flag): `tactic:execution -vendor:splunk`. Standalone `-kind:`/`-field:`/`-value:` drop every rule carrying a matching predicate leaf (`type:rules -kind:is_null`)
`field:"…"` / `value:"…"`	Quoted value = anchored exact match (also allows spaces): `value:"net user"`
`a,b`	Comma = OR inside one operator (`vendor:sigma,elastic`, `severity:high,critical`); repeating a facet merges the same way. `field:`/`value:` never split (literal commas)
`vendors:` / `stage:`	Singular and plural spellings fold to the canonical operator and value: `tactics:` = `tactic:`, `type:event` = `type:events`, `correlation:sequences` = `correlation:sequence`, `has:thresholds` = `has:threshold`
`"quoted phrase"`	Exact-match a multi-word phrase (free text)