Malicious Office (OOXML) / .DOCX — malware analysis report

Static analysis result for SHA-256 15ca85dae71b8e65…

MALICIOUS

Office (OOXML) / .DOCX

623.0 KB
MD5: 698d0d84f439beded0395f92428ec4f6 SHA-1: f0b551cbfdf1ca84f8334814fb0f2a7e0097eac7 SHA-256: 15ca85dae71b8e65d823b28eb8f75476aa28a50dd7f18ed883120400dc8f6a56
282 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is a DOCX file that imports an RTF document via altChunk, which contains an OLE object exploiting CVE-2017-11882. This vulnerability allows for arbitrary code execution when the Equation Editor is activated. The embedded RTF file, Latvia.rtf, is the primary component responsible for the exploit.

Heuristics 8

  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    (in altChunk RTF word/Latvia.rtf) 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.
  • altChunk imports embedded RTF (RTF injection) critical OOXML_ALTCHUNK_RTF
    Document inlines an embedded RTF via an aFChunk relationship and a <w:altChunk> body element. This is the canonical RTF-injection wrapper used to smuggle RTF exploits (Equation Editor / URL Moniker / objdata) past DOCX-only scanners. Word opens the wrapper and executes the RTF inline. Recursing into the RTF for the exact exploit primitive.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    (in altChunk RTF word/Latvia.rtf) 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.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    (in altChunk RTF word/Latvia.rtf) 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
    (in altChunk RTF word/Latvia.rtf) RTF contains ~2818KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    (in altChunk RTF word/Latvia.rtf) RTF contains 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    (in altChunk RTF word/Latvia.rtf) 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://opendope.org/xpaths
    • http://opendope.org/conditions
    • http://opendope.org/questions
    • http://opendope.org/components
    • http://opendope.org/SmartArt/DataHierarchy
    • http://schemas.openxmlformats.org/wordprocessingml/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/math
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/drawingml/2006/wordprocessingDrawing
    • http://schemas.openxmlformats.org/drawingml/2006/main
    • http://schemas.openxmlformats.org/schemaLibrary/2006/main
    • http://schemas.openxmlformats.org/drawingml/2006/chart
    • http://schemas.openxmlformats.org/drawingml/2006/chartDrawing
    • http://schemas.openxmlformats.org/drawingml/2006/diagram
    • http://schemas.openxmlformats.org/drawingml/2006/picture
    • http://schemas.openxmlformats.org/drawingml/2006/spreadsheetDrawing
    • http://schemas.microsoft.com/office/drawing/2008/diagram
    • http://schemas.openxmlformats.org/officeDocument/2006/bibliography
    • http://schemas.openxmlformats.org/drawingml/2006/compatibility
    • http://schemas.openxmlformats.org/drawingml/2006/lockedCanvas

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00003a12.bin
dd12cb7768d36cd8f7b7f23c2409fe2dfd3e08e1c7324e4329ca5d75faaa3b33
rtf-objdata-decoded RTF \objdata at offset 0x3A12 1421653 bytes
objdata_01_off002c4d0f.bin
cfdb4a077c5f246e92e6322395cebc5a3dcf8a28c92ec8882aadb5231c9a8a69
rtf-objdata-decoded RTF \objdata at offset 0x2C4D0F 584266 bytes