Malicious RTF — malware analysis report

Static analysis result for SHA-256 91b02f86e1df64d7…

MALICIOUS

RTF

1.17 MB First seen: 2022-10-20
MD5: cc819574a51212e651033ff382b3a044 SHA-1: e2a4845efd633958f610e4b9cba76f0f1285b94f SHA-256: 91b02f86e1df64d74ac294d2ec95ed5bee8e21891c6deab944bbdf45b297fa0d
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability through the Equation Editor. This exploit is designed to execute arbitrary code, likely to download and run a secondary payload. The presence of decoded object data further supports the exploitation attempt.

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_off00000f58.bin
1e4770cf9832212843c3eaf55e4486fe02f79c08b13123d075b08575bb6944f8		 rtf-objdata-decoded RTF \objdata at offset 0xF58 52573 bytes
objdata_01_off0002e031.bin
d58e45cc3a60ce012b53972ea70846c80b4219924e4d59541626e9dbb3083e1d		 rtf-objdata-decoded RTF \objdata at offset 0x2E031 254566 bytes

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