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

Static analysis result for SHA-256 91c31cd578b3b390…

MALICIOUS

Office (OOXML) / .XLSX

634.9 KB Created: 2010-06-04 08:55:28 UTC Authoring application: Microsoft Excel 15.0300 First seen: 2023-09-18
MD5: c246d5985826dede97280f4576b4e4de SHA-1: b3066c8c02fc51ec15bd22675e797b799121357a SHA-256: 91c31cd578b3b39026aea93fbb5bdbdbf568d777c27870f10b268b6677b0fb5d
100 Risk Score

Malware Insights

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

The sample is an Office document containing an embedded OLE object, specifically identified as a vulnerable Equation Editor object. This object carries a payload-sized Ole10Native stream, indicating it's designed to exploit the Equation Editor vulnerability. The large size and anomalous header of the Ole10Native stream strongly suggest it contains a secondary malicious payload.

Heuristics 3

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/yd.zE0tbY 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
7e3f08b4f8a5510cc1380eb4c68a1bf1fcef666f165aa46ed9303c79e99b119d		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/yd.zE0tbY 911872 bytes
ooxml_oleobject_00_ole10native_00.bin
262700d3944d2da550d697bf56b6523dd9d6d898e4c8b21d703819aaf4d23218		 ole-package OOXML xl/embeddings/yd.zE0tbY Ole10Native stream: oLe10NATIVE 902525 bytes

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