Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 7f55a7b60a243743…

MALICIOUS

RTF / .DOC

3.3 KB First seen: 2023-03-17
MD5: a5a6fbe5e7f86784d14ce1f4d7672f6b SHA-1: c8b9fc16cea841705b1b80152cc95f3322799c80 SHA-256: 7f55a7b60a243743fe8f8f25220e8aae506d985ff963587200329f229cca2248
200 Risk Score

Malware Insights

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

The RTF document contains OLE object data and specifically triggers the Equation Editor vulnerability (CVE-2017-11882). The presence of \objupdate and \objdata sections, along with the Equation Editor ProgID, indicates an attempt to automatically activate and execute embedded malicious content. This is a common delivery mechanism for exploiting this known vulnerability.

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.
  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000071.bin
eafc2bfd6584c19ff52092a9e1afde339dd87bbbc0b5bbc212851a2f8654443b		 rtf-objdata-decoded RTF \objdata at offset 0x71 1603 bytes

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