Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 e37be953d1cca688…

MALICIOUS

RTF / .DOC

188.9 KB First seen: 2023-01-30
MD5: 4b7c60a4c83598dfeedd4bfeb4c055a5 SHA-1: 5f8f6dffbc4dec2727ed06ad44e24f8fd36d73dc SHA-256: e37be953d1cca68849cd2c580e402f7cdf9f4a382b894481befa1bcaa719e0d7
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that triggers the Equation Editor vulnerability (CVE-2017-11882). This technique is commonly used to execute arbitrary code upon opening the document, likely to download and run a secondary payload. The presence of RTF_OBJDATA, RTF_OBJEMB, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristics strongly indicates this exploit vector.

Heuristics 5

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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.
  • \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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000006c.bin
bc7c96ca0385c7028d5a5183d2ac8608a3a108c11d1dac5a12ad29a5ad911ccc		 rtf-objdata-decoded RTF \objdata at offset 0x6C 58981 bytes

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