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

Static analysis result for SHA-256 acc161e322548e4c…

MALICIOUS

Office (OOXML) / .XLSX

2.59 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: c9b2003f6241249cb795467e751f1933 SHA-1: 1f92c290e8cba145aebac80986b857451356d4a8 SHA-256: acc161e322548e4c20d6c33aef9467e8f1fb20c69231476568d8e0932acdb5d8
150 Risk Score

Malware Insights

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

The sample is an Office Open XML spreadsheet containing an embedded OLE object, specifically identified as a vulnerable Equation Editor object. Heuristics indicate anomalies in the Equation Editor's native stream, consistent with exploitation of CVE-2018-0798. This suggests the file is designed to exploit this vulnerability to execute a secondary payload, likely embedded within the OLE object.

Heuristics 6

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/oleObject1.bin contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • CVE-2018-0798 — anomalous Equation Editor native stream high CVE likely CVE_2018_0798_EQUATION_NATIVE_ANOMALY
    Embedded Equation Editor OLE data contains anomalous native stream bytes consistent with a CVE-2018-0798-style Equation Editor exploit. This is treated as likely CVE evidence because the Equation object is malformed and payload-like, but it does not match the exact public matrix-overflow byte signature.
  • 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
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
    URL http://www.day.com/dam/1.0
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/tiff/1.0/
    • http://purl.org/dc/elements/1.1/

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
5f86afa66f8e74fdc9b562c362a5f655f8bf9ee2b8b7ebee945dc1dfaf17b307		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 1807872 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.98, consistent with packed or encrypted content.
ooxml_oleobject_00_ole10native_00.bin
25f479218e30041e01b00fb2a951405b936734181eaba18c6895b290a4758c38		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: oLE10NAtIVe 1791473 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.
emf_00.emf
ed892c4e9c0e2323d8e5e650ec452c21faafe0ab980b60f9ce50e901dde367ef		 ooxml-emf OOXML EMF part: xl/media/image8.emf 653280 bytes

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