Malicious RTF — malware analysis report

Static analysis result for SHA-256 8d76236cce15219a…

MALICIOUS

RTF

2.20 MB First seen: 2021-10-01
MD5: e62c1306951d5b8e2e4c475f24ecbc2a SHA-1: a6ee70ea1e326e1c58482056e1dfc73481a08567 SHA-256: 8d76236cce15219a64c2957d902fb287645d5a3b7768de07a7561c40f85da00a
180 Risk Score

Malware Insights

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

This RTF document was flagged as malicious. Specific URLs and indicators for this sample are listed in the indicators section.

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_off000011e1.bin rtf-objdata-decoded RTF \objdata at offset 0x11E1 47809 bytes
SHA-256: 38e94ddff75544564c132f627e1a357364bbc44191e99d4c02ac3829643028da
objdata_01_off0002aefe.bin rtf-objdata-decoded RTF \objdata at offset 0x2AEFE 543771 bytes
SHA-256: 1dff60c32303d58fd426d1215689e547377c88210d425e277a4a202bc2e03050

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