Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 2ab81ddd9dd9c9ac…

MALICIOUS

RTF / .DOC

48.5 KB
MD5: 9d8a33113e892c3b6e9bf6fa0bd54d98 SHA-1: 81f677df6083e41d1489c4a19e421177d1d91bc7 SHA-256: 2ab81ddd9dd9c9ac1037d054db9a444547212bff5f46795eb0021f9cab4e9cf0
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_OBJDATA, RTF_OBJEMB, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics indicates that the file is designed to trigger this exploit. The extasciitilde{}objupdate directive forces the OLE object to activate, leading to arbitrary code execution.

Heuristics 5

  • 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.
  • 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.
  • \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.
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000540.bin
f785dcb1c86b8563c5673f7bd17c056c126dfb9bc2bb55b1dfe2d7cf03f1f7a5		 rtf-objdata-decoded RTF \objdata at offset 0x540 1699 bytes

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