Malicious RTF — malware analysis report

Static analysis result for SHA-256 4937730a038a89a6…

MALICIOUS

RTF

1.07 MB First seen: 2022-11-23
MD5: e029755d713d9fe984b86604a0f8b4f8 SHA-1: 0b08f3f9d7e00fc1ca9d0aa3b05a54ec7b47ee0f SHA-256: 4937730a038a89a65fae406685e7e59b6616d3812d93e55fa6820be06ed4d720
180 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability through the Equation Editor. The `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics confirm this exploit. The `RTF_OBJUPDATE` heuristic indicates that the OLE object is forced to activate, leading to arbitrary code execution. The document body content appears to be malformed or obfuscated script fragments, not directly indicative of a specific lure.

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_off0000128a.bin
de1a1201a999360f6db13794d1152dba3563fa5db5682646e1a458e50bd20ba9		 rtf-objdata-decoded RTF \objdata at offset 0x128A 191933 bytes
objdata_01_off00068d3f.bin
275989a855ed573de58bb17016afb8dbd79952af0073c34a3ce49b1d7275cf1a		 rtf-objdata-decoded RTF \objdata at offset 0x68D3F 140544 bytes

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