Malicious RTF — malware analysis report

Static analysis result for SHA-256 a9fcb40691440ea6…

MALICIOUS

RTF

4.9 KB First seen: 2021-06-13
MD5: f80917f5435e88f3c3182d753f5ea7f1 SHA-1: e24ee1652d9be461b8a3d1de43a1f35989f4be73 SHA-256: a9fcb40691440ea6ce258ba325918454168efc0f503d2e5892da38cb09b760b2
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains multiple indicators related to the Equation Editor vulnerability (CVE-2017-11882), including OLE object data and specific ProgIDs. This vulnerability is commonly exploited to achieve arbitrary code execution on the victim's machine, likely as part of a spearphishing attachment campaign.

Heuristics 5

  • Split hex Equation Editor ProgID + OLE object critical CVE likely 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.
  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000f4.bin rtf-objdata-decoded RTF \objdata at offset 0xF4 2176 bytes
SHA-256: ca858fe4c52cd2cea60aacd7ff50108d8565de055f5d2184c051ac698a8b53c8

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