Malicious RTF — malware analysis report

Static analysis result for SHA-256 2c8b765610dd1577…

MALICIOUS

RTF

1.78 MB First seen: 2021-07-02
MD5: 28de94fd4eb97e24bc2aa85c167b9b6d SHA-1: 47800f7586bc4abe1dfcff90ec53db201c67a64f SHA-256: 2c8b765610dd1577e94ac32ff9268dfe9cd2ffe7a420c88b57cae37e72ea84f7
340 Risk Score

Malware Insights

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

The RTF file contains multiple indicators of malicious activity, including OLE objects and specific heuristics pointing to the CVE-2017-11882 Equation Editor vulnerability. The presence of hex-encoded PE headers within the RTF data strongly suggests that the file is designed to drop and execute a secondary payload. ClamAV also detected this as Rtf.Dropper.Agent.

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: 9f0adad8350286a3f3ee0964585ba3451bec10a372fe715f2535fc921d67aa39
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 420102 bytes
SHA-256: abb5ea9772b4c06e82eb7f9bd9b8d582ec8528a9cb065444506e81a5d4fbc223

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