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

Static analysis result for SHA-256 efd26f5d273cb058…

MALICIOUS

Office (OOXML) / .XLSX

2.54 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: 6c76340835d5e1cfd1420dee2ba58dbb SHA-1: afa8a72df04f3aa8fafb9449e0e3993141e82769 SHA-256: efd26f5d273cb0580fa9cc8d0a998cc202d22ea217e3cbfa1721a564ac0c05d6
150 Risk Score

Malware Insights

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

The sample is an Office document containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate this object is anomalous and carries a high-entropy payload, strongly suggesting exploitation of CVE-2018-0798. This technique is commonly used to download and execute a second-stage payload.

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
61047cb88cb5899ae440ed64271881e5b084b260c368d0eccb99b565a16ae826		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 2086400 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
f864c66c5ce057b93a417cf482aaf3141ecea36dcb5471324c3ac85c7160edc0		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: oLe10NaTivE 2067646 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
a8c0136e25bd74f04303770a3c32267a27419032a4a735a76a44e34f0baf14eb		 ooxml-emf OOXML EMF part: xl/media/image11.emf 653280 bytes

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