Malicious RTF — malware analysis report

Static analysis result for SHA-256 1f8186689ee77103…

MALICIOUS

RTF

3.4 KB First seen: 2022-12-19
MD5: e590c10818e1261b96d84b79fa3a3992 SHA-1: 4d91de592ae06598ec03c00a133e233e1075b0dc SHA-256: 1f8186689ee771039ea2c47bbbc1d5ada9d194847a597b0c5739ef3c31e06837
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains an embedded OLE object that leverages a known vulnerability in Microsoft Equation Editor (CVE-2017-11882). The object is automatically linked and updated, forcing activation and triggering code execution. This technique is commonly used to download and execute 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.
  • 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_off00000081.bin
d9681f7b9d88552f67685979d1519a64cb351cb385e58a43870e485cd16e24b0		 rtf-objdata-decoded RTF \objdata at offset 0x81 1648 bytes

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