Malicious RTF — malware analysis report

Static analysis result for SHA-256 5e0c9ae3d220d6e5…

MALICIOUS

RTF

12.2 KB First seen: 2020-08-25
MD5: 33aefeba3f56df4b2300763d91dedf8c SHA-1: 6c4fe304bca37549aaac14277dd26838a9d7722d SHA-256: 5e0c9ae3d220d6e59d934fdc7cfae2ab70c2a1dc268d5beaf9c041ab5f3973df
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 related to Equation Editor, specifically triggering CVE-2017-11882. This exploit is designed to execute arbitrary code, likely leading to the download and execution of a secondary payload. The presence of RTF_OBJDATA, RTF_OBJAUTLINK, and RTF_OBJUPDATE heuristics further confirms the exploitation of OLE objects for malicious purposes.

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_off00001c61.bin rtf-objdata-decoded RTF \objdata at offset 0x1C61 1891 bytes
SHA-256: aa07021e95a690386d4a42ed08602b23dd27de6f89d5c1f2c8fca722e5d9bda0

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