Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 fba91acce81d311b…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-03-02
MD5: aab1295dce5a11f5ff3fb8cec6bbc8e4 SHA-1: 23ac4e0a06f48171c6ba3eca6624c3d063392d53 SHA-256: fba91acce81d311b150ad67f597124023c758af0f0b7611207ae221c0c05784f
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains embedded OLE objects and specifically triggers the Equation Editor vulnerability (CVE-2017-11882). This exploit is designed to execute arbitrary code, likely to download and run a second-stage payload. The presence of 'Equation.3' and the CVE-2017-11882 activation heuristic strongly indicate this attack vector.

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_off000012c5.bin
eae8195ba7b30fc016f831d0673e8cd4d4c5e8c326a9744888798a678f5e9809		 rtf-objdata-decoded RTF \objdata at offset 0x12C5 26976 bytes
objdata_01_off00019f0e.bin
15cd899df55c0259e9e82ce1dea3dfe3468cce5957b8b3d286308d031a7aecf2		 rtf-objdata-decoded RTF \objdata at offset 0x19F0E 461608 bytes

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