Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c072111ff233e6a6…

MALICIOUS

RTF / .DOC

97.8 KB First seen: 2023-02-24
MD5: fa22e183fc91ed16a9f9535e675cf1c7 SHA-1: 432ac365c686764d69c5b97443099e5fbbd4c733 SHA-256: c072111ff233e6a6cc7634eaf173cab37520fe3c5d98436723e022b3c4ff40b7
220 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability through an embedded Equation Editor object. The document body contains a lure related to financial statements, instructing the user to 'Enable editing', which is a common tactic to bypass security measures. The embedded OLE object and specific Equation Editor ProgID strongly indicate exploitation of this known vulnerability for initial execution.

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_off00002253.bin
0982d2a825ee74145716737412a14a6b7739bd32fad197c4d6ec2059c4da9765		 rtf-objdata-decoded RTF \objdata at offset 0x2253 2006 bytes

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