Malicious RTF — malware analysis report

Static analysis result for SHA-256 b70c112ed968b084…

MALICIOUS

RTF

25.9 KB First seen: 2022-11-29
MD5: 9030afe25461e39f11f8f7239217ca24 SHA-1: a47f1de11c15e5901110c29f318314ffbb65326a SHA-256: b70c112ed968b0846a461d7d3c8e3681383fe28a8b5099c6201cb5bc263c2785
220 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The presence of ".objdata", ".objautlink", and ".objupdate" heuristics, along with the specific class name "EQUAtIOn.3", strongly indicates exploitation of this known vulnerability. The document also contains a lure instructing the user to 'Enable editing', a common tactic for macro-based or exploit-based document malware.

Heuristics 6

  • 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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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 1 \objdata section(s) — embedded OLE objects
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00005453.bin
4e1cc87ac921d4d20c1d5993768467060da95f9b54d7eeecf814d74c8e573eaa		 rtf-objdata-decoded RTF \objdata at offset 0x5453 1424 bytes

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