Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e8126a53862ab1bc…

MALICIOUS

RTF / .DOC

28.2 KB First seen: 2022-11-23
MD5: 9b67902bcc37d5c7d253b2e1667f6339 SHA-1: e03911af1c359baeb74d73a0078ba1478dc368d5 SHA-256: e8126a53862ab1bc283a6850261c94de1e85606ed02639fa555897c8f8d4beb9
200 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 an embedded OLE object specifically identified as related to CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of \objdata and \objupdate directives indicates an attempt to force OLE activation, which is a common delivery mechanism for this exploit. The document also contains a lure instructing the user to 'Enable editing', further supporting its role as a malicious dropper.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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_off000054df.bin
daf0da235c2fa3726004bd4cc18e2bc49b5cf5ffd900261959748a167ebe4a66		 rtf-objdata-decoded RTF \objdata at offset 0x54DF 1555 bytes

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