Malicious RTF — malware analysis report

Static analysis result for SHA-256 8b90a294d782aecd…

MALICIOUS

RTF

2.79 MB First seen: 2019-05-16
MD5: 939311911a819ac75aea23761d5027b9 SHA-1: 775e16788ac4dc232afeb77f1988289eac2744b8 SHA-256: 8b90a294d782aecdbd9b5cb20c8225d4dfed58dc0f220db9ec9c2c09d96d697d
464 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The RTF file contains multiple indicators of exploitation for CVE-2017-8570, including Composite Moniker and Equation Editor CLSID firings. The embedded OLE object data, particularly objdata_06_off0002d62f.bin, likely contains the second-stage payload, as indicated by the presence of a PE header in hex data and ClamAV detections on extracted artifacts. The exploit facilitates client execution by leveraging the vulnerability to drop and run a malicious binary.

Heuristics 11

  • Composite Moniker — CVE-2017-8570 (drops SCT script) critical CVE related CVE_2017_8570
    RTF \objdata decodes to OLE data containing the Composite Moniker — CVE-2017-8570 (drops SCT script) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • 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.
  • ClamAV: Win.Trojan.Quasar-7172313-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Trojan.Quasar-7172313-0
  • 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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~2740KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 7 \objdata section(s) — embedded OLE objects
  • OlePres presentation stream in RTF OLE object medium RTF_OLEPRES_STREAM
    RTF contains an embedded OLE object with an OlePres presentation stream. OlePres is an OLE presentation marker and is not enough on its own to identify CVE-2025-21298.
  • 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.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2003/wordml In RTF body

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000031.bin rtf-objdata-decoded RTF \objdata at offset 0x31 1370316 bytes
SHA-256: e6ee38393137ac7b7763f513af84d600be81c2c8c2838afea719cfb84f0907f4
Detection
ClamAV: Win.Trojan.Quasar-7172313-0
Obfuscation or payload: likely
Carved artifact entropy is 7.86, consistent with packed or encrypted content.
objdata_01_off002b582f.bin rtf-objdata-decoded RTF \objdata at offset 0x2B582F 31676 bytes
SHA-256: 8e1be3feb782a829ff258a0e054e4c260ab6864e307e975e6874709ef91bf7cf
objdata_02_off002c4fdf.bin rtf-objdata-decoded RTF \objdata at offset 0x2C4FDF 381 bytes
SHA-256: 3458e1d85410d8b0a08c68591e0912e582782375d61f43343a9a5d6983b8c436
objdata_03_off002c5315.bin rtf-objdata-decoded RTF \objdata at offset 0x2C5315 788 bytes
SHA-256: 9f474d871d5073e0821f436fc51680b1a4730c0843652540921f90acc5b5f4a5
objdata_04_off002c59bb.bin rtf-objdata-decoded RTF \objdata at offset 0x2C59BB 2633 bytes
SHA-256: 1feb5f150bb35566d1a01fc59a357dc0ea34bc7498e0ec99bd939f6f848044b0
objdata_05_off002c6ee3.bin rtf-objdata-decoded RTF \objdata at offset 0x2C6EE3 4679 bytes
SHA-256: 82391dd064c94b96ac16e2f26524d4d6c5630381aa5a88c7c3d5e8aac77bbfc4

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