Malicious RTF — malware analysis report

Static analysis result for SHA-256 7d71398d505456af…

MALICIOUS

RTF

8.0 KB First seen: 2021-08-25
MD5: a67a4a92e5e6c4d6ae5046003663717b SHA-1: 59c521a8b67032ab5ee2198405e4e19afe156179 SHA-256: 7d71398d505456af479bc96e692f002040a8b9fb9373588bc624740147662295
200 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically targeting CVE-2017-11882, which is a known vulnerability in Microsoft Equation Editor. The presence of \objdata, \objupdate, and the specific ProgID 'eqUaTiON.3' strongly indicate exploitation of this vulnerability for client execution. No document body or script content was available for further analysis, but the exploit itself is sufficient to classify the file as malicious.

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 1 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000ce8.bin rtf-objdata-decoded RTF \objdata at offset 0xCE8 1752 bytes
SHA-256: ca544a553a1f16318af3a9bf09f735e988930a7d874f21279bf76ea52b92d24a

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