Malicious RTF — malware analysis report

Static analysis result for SHA-256 5b608070fbf9510d…

MALICIOUS

RTF

2.7 KB First seen: 2022-11-29
MD5: 68a9b572a704a702c7df692c7bad5e96 SHA-1: 059f799f923edfb81eaeca72d64b9103ef33430e SHA-256: 5b608070fbf9510d7213a66e77d9704205fe964cc37e95986d87de96e3247d2a
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.003 Windows Command Shell

The RTF document contains an embedded OLE object that leverages a known vulnerability in Microsoft Equation Editor (CVE-2017-11882). This vulnerability allows for the execution of arbitrary code upon activation, likely to download and execute a secondary payload. The presence of RTF_OBJAUTLINK and RTF_OBJUPDATE heuristics further indicates that the embedded object is designed to be automatically activated.

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_off00000077.bin
cc66f6662911c201c2bba6e09482c71c7713d08e9397e20cae18223527154862		 rtf-objdata-decoded RTF \objdata at offset 0x77 1271 bytes

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