Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c6a2d9e0700a2fd8…

MALICIOUS

RTF / .DOC

861.0 KB First seen: 2022-09-19
MD5: aab9061c672791c3c787e3aa05547de1 SHA-1: 14b16e38d9e0609c1f8bbe9fd8290abc3fc4f8ba SHA-256: c6a2d9e0700a2fd82aa9759f8672f0bed78aef7de0e5a9b9f85f8450bbb25a5a
180 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking T1204.002 Malicious File

The sample is an RTF document that heavily leverages OLE objects and specifically targets the Equation Editor vulnerability (CVE-2017-11882). The presence of \objdata and \objupdate directives, along with the critical RTF_EQUATION_EDITOR heuristic, strongly indicates exploitation of this known vulnerability. This technique is commonly used to embed and execute malicious code, often as a downloader for further stages.

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_off000012b8.bin
ab4910a2100ee0945d495d6ba4ac0bc22e01a4cd4fa31d0de51ee12395f722ce		 rtf-objdata-decoded RTF \objdata at offset 0x12B8 81520 bytes
objdata_01_off0002f130.bin
8241f500b6f66c0010a61e3e66b293b7e5e246b297d9c6a44403288dc5895294		 rtf-objdata-decoded RTF \objdata at offset 0x2F130 140710 bytes

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