Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 f78d0da436abd6c7…

MALICIOUS

RTF / .DOC

10.2 KB First seen: 2022-10-10
MD5: eb13ddeb83d7f8f3762ef8c7a3f6625b SHA-1: 8cd15f22a9ceca1a085a014bdb25eea2b85ede4f SHA-256: f78d0da436abd6c77f60d2123e039974e5f1ac6fdf2cac9e8126e784691d97ac
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 containing a malformed Equation Editor OLE object, which is a known exploit for CVE-2017-11882. The document body contains a lure instructing the user to 'Enable editing', indicating a social engineering attempt to bypass security measures. The embedded OLE object is designed to trigger the exploit upon activation, likely leading to the execution of a secondary payload.

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_off00000d6d.bin
2a42818e37eac5240b1bb86fe9e29cc67b9fe494e96a77c4f744b89fc361ca17		 rtf-objdata-decoded RTF \objdata at offset 0xD6D 1982 bytes

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