Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c1c40390e69f3c9d…

MALICIOUS

RTF / .DOC

27.5 KB
MD5: 6c1979c8717437d4bf1233200a0a23a1 SHA-1: a7a13e190d98fb1d7f064bb78d8d0f50a8bd6ce3 SHA-256: c1c40390e69f3c9d7fac84db9a0783ff6384b4f4de481142018331392cccf483
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.001 PowerShell

The file is an RTF document that contains embedded OLE object data, specifically triggering the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics confirms the exploitation of this known vulnerability. The objupdate directive forces OLE activation, leading to the execution of the embedded malicious object. The document body is heavily obfuscated and does not provide direct clues to the ultimate payload, but the exploit itself is the primary attack vector.

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_off00001603.bin
343568c093c22f335499d3fe6da0c57371571f564364023d656040bc129b4bf2		 rtf-objdata-decoded RTF \objdata at offset 0x1603 2241 bytes

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