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

Static analysis result for SHA-256 3964f3eb14c348d5…

MALICIOUS

Office (OOXML) / .XLSX

1.14 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: 1dffded46a39053ed2e4c5d178cb1a87 SHA-1: 51fb859291867bdba9dea197f4788f8ffcb76f8d SHA-256: 3964f3eb14c348d5578e1b758c9cb25d792aa287c24b57f8371729996dc118fc
170 Risk Score

Malware Insights

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

The sample contains an embedded Equation Editor OLE object, which is a known vector for exploiting vulnerabilities. The OLE10Native stream within this object exhibits anomalies suggesting it carries a payload. ClamAV detection as 'Xls.Downloader' further supports its malicious nature. The embedded OLE object likely facilitates the download and execution of 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.
  • ClamAV: Xls.Downloader.af2fa5c5d0587870-9978799-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.af2fa5c5d0587870-9978799-0
  • 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
  • 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
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    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 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
d5dde2e33d35fbc0257f7f0a4eaab3d2d35a493d91f609da9037fe57ba0c2294		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 1016320 bytes
ooxml_oleobject_00_ole10native_00.bin
bb93da0f100334f73770330f8d57542b3a6b3cea4bc47cea3c0654c66f6d41c3		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OLE10nAtIVe 1005825 bytes
ooxml_oleobject_01.bin
6e211d0d8130eb99eeaa561fc597da6633c51a8af7d3be06f3ecae003d041c07		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject2.bin 10240 bytes
ooxml_oleobject_01_ole10native_00.bin
59fb77315591a55324873430963abffa12244adc4996302250a87d8a758a5796		 ole-package OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native 8667 bytes
emf_00.emf
1c23e8b05b5fdc78ce55deed924f35da2446b8523f319c1baf30ecee9dd6c9f9		 ooxml-emf OOXML EMF part: xl/media/image5.emf 648132 bytes
emf_01.emf
c024f3acb1e2b6bc73248f2aaf32151834620299d4b34f5c5a0d695db8e3fa4a		 ooxml-emf OOXML EMF part: xl/media/image6.emf 7608 bytes

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