Malicious RTF — malware analysis report

Static analysis result for SHA-256 b51576eb10924777…

MALICIOUS

RTF

1.74 MB First seen: 2019-09-30
MD5: 8b78263230f17668c66ecc24fc2b6c76 SHA-1: 77ebe2e491522fb5c84a34029cb547c3f25f5846 SHA-256: b51576eb1092477721ecb00dceb46c7c941581d75b9ed628fdfbeb550766327b
282 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains multiple indicators of exploitation, including critical firings for CVE-2017-8570 and the Equation Editor CLSID. The presence of large, hex-encoded OLE object data suggests a hidden payload. The CVE-2017-8570 firing specifically indicates the dropping of an SCT script, which is likely executed to achieve the malicious objective.

Heuristics 8

  • 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.
  • \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 ~1625KB 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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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://ns.adobe.com/xap/1.0/ In RTF body
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#In RTF body
    • http://ns.adobe.com/xap/1.0/mm/In RTF body
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000025.bin rtf-objdata-decoded RTF \objdata at offset 0x25 229 bytes
SHA-256: bdf6de0a64b3411ca5229f989a8704bb9f2ac8eac0d3b0c83ab62136585dd012
objdata_01_off0000021a.bin rtf-objdata-decoded RTF \objdata at offset 0x21A 812771 bytes
SHA-256: a88fb2ef8090c701045d0a7bfe121bef1a5a49f21c783a3a854e1d412f1de032
objdata_02_off0019105c.bin rtf-objdata-decoded RTF \objdata at offset 0x19105C 1116 bytes
SHA-256: 93ac402ce898ee6f1b9e776ff4289854d3037d6d65706352bd0b71bc418a2ddd
objdata_03_off00191947.bin rtf-objdata-decoded RTF \objdata at offset 0x191947 86355 bytes
SHA-256: 35675dceaae981645f31bff5605c047979f71fa578537bc02e6d585774d7c287
objdata_04_off001bbc1f.bin rtf-objdata-decoded RTF \objdata at offset 0x1BBC1F 399 bytes
SHA-256: dc3da5e38801b5fa23cf99248f674a9b06d9120c119f995001155e4bc263978f
objdata_05_off001bbf71.bin rtf-objdata-decoded RTF \objdata at offset 0x1BBF71 937 bytes
SHA-256: e21955e19ee5e9c33caa29d20574aba20d6cc02b855734ac20377ad351eddf3c
objdata_06_off001bc72a.bin rtf-objdata-decoded RTF \objdata at offset 0x1BC72A 2633 bytes
SHA-256: 27c6d10cfe7974ebf40c1200cc005f9878cc37b7d49ece9cbc396d700c38918a

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