Detection rules › Sublime MQL

Attachment: MS Office or RTF file with Shell.Explorer.1 com object with embedded LNK

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

Detects embedded Shell.Explorer.1 COM objects containing LNK files within various file types.

Threat classification

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

CategoryValues
Attack typesMalware/Ransomware
Tactics and techniquesEvasion

Event coverage

Rule body MQL

type.inbound
and any(attachments,
        (.file_type == "rtf" or .file_extension in $file_extensions_macros)
        and any(file.explode(.),
                any(.scan.yara.matches,
                    strings.starts_with(.name, "ShellExplorer1_LNK_")
                )
        )
)

Detection logic

Scope: inbound message.

Detects embedded Shell.Explorer.1 COM objects containing LNK files within various file types.

  1. inbound message
  2. any of attachments where all hold:
    • any of:
      • .file_type is 'rtf'
      • .file_extension in $file_extensions_macros
    • any of file.explode(.) where:
      • any of .scan.yara.matches where:
        • .name starts with 'ShellExplorer1_LNK_'

Inspects: attachments[].file_extension, attachments[].file_type, type.inbound. Sensors: file.explode, strings.starts_with. Reference lists: $file_extensions_macros.

Indicators matched (2)

FieldMatchValue
attachments[].file_typeequalsrtf
strings.starts_withprefixShellExplorer1_LNK_