Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 38f284c6ac68831d…

MALICIOUS

RTF / .DOC

3.73 MB First seen: 2022-06-23
MD5: fd00d713c843371c82be116049b5a6d9 SHA-1: e46e115e003d6088655a5c364d6d03551cb0e41b SHA-256: 38f284c6ac68831d066f9325b4f8508145ef62146b4c257e3c0a10fdf2305b0a
382 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects and exploits CVE-2017-11882 via the Equation Editor (Equation.3). The large amount of hex-encoded data within the objdata sections, along with the presence of a PE header, strongly suggests that a malicious executable payload is hidden and intended for execution. ClamAV detection as Rtf.Dropper.Agent-9965975-1 further confirms its malicious nature as a dropper.

Heuristics 10

  • 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.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • 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 ~1876KB 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_off000012ab.bin
88db1de41923b7e85fd45f237c722b812522638c1b2ba6e63afc71c04c97ba96
rtf-objdata-decoded RTF \objdata at offset 0x12AB 955691 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.66, consistent with packed or encrypted content.
objdata_01_off001df670.bin
ee689f3f3e104d316fdfdcc5da12c6430bbbcc7bd0a9e503676477f2b53390b6
rtf-objdata-decoded RTF \objdata at offset 0x1DF670 462748 bytes