Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 11eebdbf0b2405b9…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-15
MD5: b745b270b0fbaca2cb0773bca2dae7fa SHA-1: 81090a2e8ea664d8d509db915cdc1496ecc5819b SHA-256: 11eebdbf0b2405b9a9160de3ec2987920250ee5ba4f679a250c89e10201120ab
180 Risk Score

Malware Insights

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

The file is an RTF document that contains embedded OLE objects, specifically triggering heuristics related to CVE-2017-11882 and Equation Editor exploitation. This indicates the document is designed to exploit a vulnerability in Microsoft Office's Equation Editor to execute arbitrary code. The embedded object's class is identified as 'Equation.3'.

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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001347.bin
2e1ac4e87d1020cd5a270899a608fa5928deb9d05daa2edfe504c47a254db60c		 rtf-objdata-decoded RTF \objdata at offset 0x1347 25593 bytes
objdata_01_off00019544.bin
689965aaaf88dfda2c46136e8ee45ccbdf5d380abcba88d5f9ff529d3c59ced2		 rtf-objdata-decoded RTF \objdata at offset 0x19544 463381 bytes

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