Detection rules › Sublime MQL

Anthropic Magic String in HTML

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

Detects messages containing the specific test string 'ANTHROPIC_MAGIC_STRING' in the plain text body content.

Threat classification

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

CategoryValues
Attack typesMalware/Ransomware
Tactics and techniquesExploit

Event coverage

Message attribute
body.html
body.plain
type

Rule body MQL

type.inbound
and length(attachments) <= 3
and (
  strings.icontains(body.html.raw, 'ANTHROPIC_MAGIC_STRING_')
  or strings.icontains(body.plain.raw, 'ANTHROPIC_MAGIC_STRING_')
  or strings.icontains(body.html.display_text, 'ANTHROPIC_MAGIC_STRING_')
  or any(attachments,
         any(file.explode(.),
             strings.icontains(.scan.ocr.raw, "ANTHROPIC_MAGIC_STRING_")
             or strings.icontains(.scan.strings.raw, "ANTHROPIC_MAGIC_STRING_")
         )
  )
)

Detection logic

Scope: inbound message.

Detects messages containing the specific test string 'ANTHROPIC_MAGIC_STRING' in the plain text body content.

  1. inbound message
  2. length(attachments) ≤ 3
  3. any of:
    • body.html.raw contains 'ANTHROPIC_MAGIC_STRING_'
    • body.plain.raw contains 'ANTHROPIC_MAGIC_STRING_'
    • body.html.display_text contains 'ANTHROPIC_MAGIC_STRING_'
    • any of attachments where:
      • any of file.explode(.) where any holds:
        • .scan.ocr.raw contains 'ANTHROPIC_MAGIC_STRING_'
        • .scan.strings.raw contains 'ANTHROPIC_MAGIC_STRING_'

Inspects: body.html.display_text, body.html.raw, body.plain.raw, type.inbound. Sensors: file.explode, strings.icontains.

Indicators matched (1)

FieldMatchValue
strings.icontainssubstringANTHROPIC_MAGIC_STRING_