Malicious RTF — malware analysis report

Static analysis result for SHA-256 978d15e852f3cd2e…

MALICIOUS

RTF

1.39 MB First seen: 2021-06-20
MD5: 77348667729f593943a4de9d116bd662 SHA-1: c970548ad0c73f430248535fdfc833127d607f46 SHA-256: 978d15e852f3cd2e7b420abb7aa1cb579865ad880606981c48a67f8b86e9152e
180 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability related to Microsoft Equation Editor. This exploit allows for arbitrary code execution, likely as part of a spearphishing attachment. The embedded OLE object data and the specific Equation Editor ProgID are key indicators of this attack vector.

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 53349 bytes
SHA-256: 805850740f47a2ef47786881b8e31d56c0c5c72f83e3885028f36936a4542b3a
objdata_01_off0002ed1b.bin rtf-objdata-decoded RTF \objdata at offset 0x2ED1B 346025 bytes
SHA-256: 5d913e0bdd4543b59117490fda1dba3c38edbcd2b81c5376d07402a696f7c2ab

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