Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 64424964b84f156c…

MALICIOUS

RTF / .DOC

21.0 KB
MD5: 7b8c1c0322a2723545ea21375e4beb15 SHA-1: 822b5fbc2d38f53e5c589b620edee24c1a53aceb SHA-256: 64424964b84f156c7aad36deb421e2c3424d33954ab9ca9690c6d41b9c73253f
200 Risk Score

Malware Insights

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

The sample is an RTF document that contains embedded OLE object data, specifically triggering heuristics related to the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for arbitrary code execution, which is the primary mechanism for compromise. The presence of ".objupdate" and ".objautlink" further indicates that the embedded object is designed to be activated automatically. The attack pattern is consistent with exploiting this known vulnerability to deliver a secondary payload.

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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000016ad.bin
4d44149ca01c4ac43da15639ee590e7d67b4b23b32f9dbe22e29789139bfcdb6		 rtf-objdata-decoded RTF \objdata at offset 0x16AD 1764 bytes

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