Malicious RTF — malware analysis report

Static analysis result for SHA-256 db60b670c3a3332e…

MALICIOUS

RTF

860.8 KB First seen: 2022-10-24
MD5: b446e0cbe04b22c94d58d59e1c023e45 SHA-1: 1383bbd2209aced0e6b464a8300496f3b395efa4 SHA-256: db60b670c3a3332e919fc513db4c9c952f89e473c51c90f46c2ad3f8ef5e125a
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File Execution T1559 Component Object Model Hijacking

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability through the Equation Editor. The ".objupdate" directive forces OLE activation, which is a common technique for exploiting this vulnerability to execute arbitrary code. The decoded object data suggests the presence of VBScript, likely intended to download and execute a second-stage payload.

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_off0000126a.bin
3026000dead06d405d1404666770887d26d1ab7f00008351c01c958668a6787b		 rtf-objdata-decoded RTF \objdata at offset 0x126A 81286 bytes
objdata_01_off0002eec0.bin
88f5b6696cbfd1ccbdc3bf6178a17770f1d05944ae1f8131169743e47791e9fa		 rtf-objdata-decoded RTF \objdata at offset 0x2EEC0 140887 bytes

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