Malicious RTF — malware analysis report

Static analysis result for SHA-256 3cd156ec66ad7bb3…

MALICIOUS

RTF

1.45 MB First seen: 2019-01-11
MD5: 730f3c57abaa49b53e05d5ce8e03f561 SHA-1: 3698e704eaad31e2b4c8bdef4ccbf832ba94a966 SHA-256: 3cd156ec66ad7bb3a1d2b883754e783275d2a16e452113eab8f1303358757a8a
224 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 object data and excessive hex-encoded data within objdata sections. Crucially, it triggers the CVE-2017-8570 heuristic, indicating the exploitation of a composite moniker to drop a script. This exploit is commonly used to deliver second-stage payloads, suggesting the file's primary purpose is to facilitate further malicious execution.

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.
  • 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 ~1280KB 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
  • 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.openxmlformats.org/drawingml/2006/main In RTF body
    • http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn RTF body
    • http://schemas.microsoft.com/sharepoint/v3/contenttype/formsIn RTF body
    • http://schemas.microsoft.com/office/2006/metadata/contentTypeIn RTF body
    • http://schemas.microsoft.com/office/2006/metadata/properties/metaAttributesIn RTF body
    • http://schemas.microsoft.com/office/2006/metadata/propertiesIn RTF body
    • http://www.w3.org/2001/XMLSchemaIn RTF body
    • http://schemas.openxmlformats.org/package/2006/metadata/core-propertiesIn RTF body
    • http://www.w3.org/2001/XMLSchema-instanceIn RTF body
    • http://purl.org/dc/elements/1.1/In RTF body
    • http://purl.org/dc/terms/In RTF body
    • http://schemas.microsoft.com/internal/obdIn RTF body
    • http://dublincore.org/schemas/xmls/qdc/2003/04/02/dc.xsdIn RTF body
    • http://dublincore.org/schemas/xmls/qdc/2003/04/02/dcterms.xsdIn RTF body
    • http://schemas.microsoft.com/office/infopath/2007/PartnerControlsIn 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 640227 bytes
SHA-256: e49663555767cbdfdb2b9c5043177e9828fa9300cf85ee7913aabf07807cbd1a
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.78, consistent with packed or encrypted content.
objdata_02_off001522be.bin rtf-objdata-decoded RTF \objdata at offset 0x1522BE 1092 bytes
SHA-256: d4bc1acb790f4d56cd06070639d405330d630c9694d98fa2b3b82c6bf73da07d
objdata_03_off00152b79.bin rtf-objdata-decoded RTF \objdata at offset 0x152B79 61156 bytes
SHA-256: 18ec97518c773402cd90e610780ecdb038e26b5cda73a51aea689e728fb10be4
objdata_04_off00170973.bin rtf-objdata-decoded RTF \objdata at offset 0x170973 393 bytes
SHA-256: cc434f8b829894f9e2d49a62c39440162c7bcebb137b5685ff63adca2384b98a
objdata_05_off00170cb9.bin rtf-objdata-decoded RTF \objdata at offset 0x170CB9 914 bytes
SHA-256: 27bd5b1e1679863c8cd0257c9eb6b6ee3106b285add9281353de171771ae84d6
objdata_06_off00171444.bin rtf-objdata-decoded RTF \objdata at offset 0x171444 2633 bytes
SHA-256: fe11c27d916ab897eb94064e9631d8a29c847a6db39259bef31578da8d19fdf5

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