Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 fb000322ccae333f…

MALICIOUS

RTF / .DOC

10.4 KB First seen: 2022-03-09
MD5: cbe411671e4313df9f9362043dada9e2 SHA-1: 2056ceb5c899e8bbdc98d0ad07ce54d88a99cd46 SHA-256: fb000322ccae333ffeb91931e4869225c65997094bc379f8fd85c977eaf85527
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell

The RTF file contains embedded OLE object data and specifically targets the Equation Editor component, triggering a known vulnerability (CVE-2017-11882). The presence of `EQUatioN.3` as the class name strongly indicates exploitation of this vulnerability. The ` tf1 ouicompat onttbl 0 decor charset0 Calibri;` and ` s24 0 decor charset0 Calibri; s24` indicate that the document is likely intended to be viewed as a standard document, but the embedded OLE object and the specific Equation Editor exploit are designed to execute arbitrary code upon opening. No scripts were extracted, and the document body was truncated, limiting further analysis of the 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_off000018ca.bin
820791aaca0854f391ea3ebb4f270a3f0840b4e6d00193c244313746b5d9ff6b		 rtf-objdata-decoded RTF \objdata at offset 0x18CA 1880 bytes

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