Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 899e86d5c1923002…

MALICIOUS

RTF / .DOC

2.38 MB First seen: 2023-07-24
MD5: efff3b0834bbf50bdb7ae416a83f3cf0 SHA-1: 2d68e66ac0ca398515a71c26b0810385f3ebf880 SHA-256: 899e86d5c1923002d921ee8cf0e88c8b93ecaf43366fb4245c20525e53cd7bf5
342 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains embedded OLE objects, specifically exploiting CVE-2017-11882 through the Equation Editor. The presence of large hex-encoded data blocks and a PE header within the OLE object strongly indicates that this file is a dropper designed to execute a secondary payload. ClamAV detection as Rtf.Dropper.Agent-9965975-1 further supports this assessment.

Heuristics 9

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical 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.
  • 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
  • ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
  • \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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1505KB of hex-encoded data inside \objdata sections — may hide a payload
  • 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
  • Suspicious extracted artifact info 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0008009d.bin
8f7ff06e933deb9c1a7ec403430d120c7f419f920f733f7d66e9826fcf072ef6		 rtf-objdata-decoded RTF \objdata at offset 0x8009D 503330 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.98, consistent with packed or encrypted content.
objdata_01_off0017fc5d.bin
3f59a574464cb0ae29c567c1705b677a7d8956e9c854b74550777e407fb46a11		 rtf-objdata-decoded RTF \objdata at offset 0x17FC5D 187361 bytes

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