Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 d76844ff49e147c7…

MALICIOUS

RTF / .DOC

11.3 KB
MD5: 5ca2cd21f345b9af1dcb83321284c60f SHA-1: 858e1756867ad4c771ea5065fc5b42de2e1f0a7c SHA-256: d76844ff49e147c7c93bafadbafe15eced2ab1ab22ffe4a0fd93434bba4351f8
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell

The RTF file contains embedded OLE object data, specifically triggering the Equation Editor with a ProgID that is known to be vulnerable to CVE-2017-11882. The ".objupdate" directive forces OLE activation, leading to the exploitation of this vulnerability. This allows for arbitrary code execution, likely to download and run a second-stage payload.

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 2 \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_off00001c56.bin
041ab9c6ca0e145d7aca637beac81b824d936bfce625f95aa3b7f8d7c0685b4b		 rtf-objdata-decoded RTF \objdata at offset 0x1C56 1580 bytes

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