Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 8caf0002caebfae9…

MALICIOUS

Office (OOXML) / .XLSX

812.7 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-01-31
MD5: 76d99d4dcc95199854df9f4a021ac456 SHA-1: 576a004df6b122f3c71c07397eea1f854500100b SHA-256: 8caf0002caebfae941f4cefefea93d663a6823f5bbe1ef1bafbe757bd7edd0b5
160 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking T1204.002 Malicious File

The sample is an Excel file containing an embedded OLE object identified as an Equation Editor. This object has an anomalous Ole10Native stream, indicating it likely carries a malicious payload. ClamAV detection further supports its malicious nature as a downloader trojan.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/gCF.DBpjD6e contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • ClamAV: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0
  • Equation Editor object carries payload-like Ole10Native stream high OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY
    Embedded OLE object declares the Equation Editor CLSID but stores a large high-entropy Ole10Native stream with malformed package sizing. This is an exploit-shaped Equation/OLE payload container seen in malicious OOXML samples. It is not assigned to a specific CVE unless the MTEF/Equation Native primitive also matches.
  • Embedded OLE object medium OOXML_OLE_OBJECT
    Document contains an embedded OLE object

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
2b085abeff5adb5c4ccaf117bf7485325cbceb1ce041160ba40daa5c27d4d468		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/gCF.DBpjD6e 916480 bytes
ooxml_oleobject_00_ole10native_00.bin
d1abf05a272cd215598d1cf534054e1e66320e2807b8474d24718de70d987863		 ole-package OOXML xl/embeddings/gCF.DBpjD6e Ole10Native stream: oLE10native 907144 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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