Malicious RTF — malware analysis report

Static analysis result for SHA-256 976076d787a1f1ab…

MALICIOUS

RTF

1.82 MB First seen: 2021-07-02
MD5: 6d8e633338a645f778e2730e3b2fa80b SHA-1: acb71d93923eb699d42eadf25f8deddc63fd90ba SHA-256: 976076d787a1f1ab55a5922b2cf365214d6f0dffac074ad3aaf70b865625059f
180 Risk Score

Malware Insights

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

The RTF file contains heuristics indicating the exploitation of CVE-2017-11882 through an embedded Equation Editor object. The ".objupdate" directive forces OLE activation, which is a common method for triggering exploits in documents. The embedded OLE object data likely contains the exploit code and a secondary payload, although the exact nature of the payload cannot be determined from the provided data.

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.
  • \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 53438 bytes
SHA-256: c07cfb2cd82db6f8ab9dc1e74fac0bff3429552192560476f52c5e2bc3d69ed4
objdata_01_off0002edcd.bin rtf-objdata-decoded RTF \objdata at offset 0x2EDCD 469226 bytes
SHA-256: 7d01ee387216102daeabf80a57c8f0d8112fdee1d8864b417a3fb9d69aa1d0dd

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