Malicious RTF — malware analysis report

Static analysis result for SHA-256 2ba834bb08d5ee0e…

MALICIOUS

RTF

863.1 KB First seen: 2022-09-29
MD5: 9c6f3c5de6161efb2fc56f1aa237533b SHA-1: 0c4ee61b772733a5f258b4c2104a8805d673b827 SHA-256: 2ba834bb08d5ee0eca8fc8165fe717649d19edd488b6df5f4c1e5052b039665e
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to be used to execute arbitrary code. The decoded object data suggests the presence of a VBScript, likely intended 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000012ab.bin
b9b1b3948c9ef52fedc679623700746c111b4bf111bb70e5675fd82e8cb0a19e		 rtf-objdata-decoded RTF \objdata at offset 0x12AB 81538 bytes
objdata_01_off0002f13a.bin
3191c7b669a99e6dbec6e45083f1ba3cae1925f2a91f1d3c51265214befb2f16		 rtf-objdata-decoded RTF \objdata at offset 0x2F13A 141152 bytes

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