Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c26ce8f97d89e55d…

MALICIOUS

RTF / .DOC

3.7 KB First seen: 2022-03-21
MD5: ee3553ede3f883b7be851f6dc27f687b SHA-1: cc8368e7e0fbf4f7ff5aeecec1ed22c5316e4650 SHA-256: c26ce8f97d89e55db5ca83e1885ad989690d6ddf9fd187035f4f4c41c421acc6
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 with a ProgID indicative of Equation Editor. Heuristics confirm the presence of an Equation Editor object and its activation via \objupdate, strongly suggesting exploitation of CVE-2017-11882. This vulnerability allows for arbitrary code execution upon opening the document, likely to download and execute a second-stage 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.
  • \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_off0000009c.bin
f72a72aecc89df531d9ae0e3cf03d242c8defee60789e4ba2b4bdfbe8f500d20		 rtf-objdata-decoded RTF \objdata at offset 0x9C 1666 bytes

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