Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 50099701ba9788f6…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-15
MD5: c04b13b73c3b5128d0d07ac3fddc16d3 SHA-1: bc99ec4cb863553ce42d0def5c879edc05cc31e2 SHA-256: 50099701ba9788f6e879c8064d1336ba5119ab93225faf05b7f7aa741fb066cf
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability through the Equation Editor. This exploit is designed to execute arbitrary code. The embedded script fragments suggest an attempt to download and execute a second-stage payload, likely leveraging the Equation Editor vulnerability for initial execution.

Heuristics 5

  • 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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001347.bin
3fe9bae09b261be99a2e7040bf5c1bec2d8bdb786c6b57aff49de96fbab199d2		 rtf-objdata-decoded RTF \objdata at offset 0x1347 25591 bytes
objdata_01_off00019540.bin
689965aaaf88dfda2c46136e8ee45ccbdf5d380abcba88d5f9ff529d3c59ced2		 rtf-objdata-decoded RTF \objdata at offset 0x19540 463381 bytes

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