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

Static analysis result for SHA-256 599aa910f87c1b2e…

MALICIOUS

Office (OOXML) / .XLSX

1.17 MB Created: 2021-04-19 06:10:33 UTC Authoring application: Microsoft Excel 12.0000
MD5: a0c40786b12eb6198c23677c548c6831 SHA-1: c2535bc202bc4e5799569a9ae9d8390def57fcc0 SHA-256: 599aa910f87c1b2ee94b34e3423acdb847cc43eb4af5bfc49f9fe04900557585
100 Risk Score

Malware Insights

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

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate that this object carries a payload-like Ole10Native stream with an anomalous header, strongly suggesting exploitation of a known Equation Editor vulnerability (e.g., CVE-2017-11882). No document body or scripts were extracted, but the presence of the anomalous OLE object is sufficient to infer a malicious intent to exploit this vulnerability for payload delivery.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/0ywtC.aAuB4 contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
294ed5491525d65ffd612ddc8579b0d8aee16a33511af13f76bd28ba7b809826		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/0ywtC.aAuB4 1062400 bytes
ooxml_oleobject_00_ole10native_00.bin
d8956a405bef967312bf2c0f284e69d80375c448aa04cd2c89a6b7df6ab54ebc		 ole-package OOXML xl/embeddings/0ywtC.aAuB4 Ole10Native stream: OlE10NAtIVe 1051138 bytes

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