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

Static analysis result for SHA-256 2da8790cff57665b…

MALICIOUS

Office (OOXML) / .XLSX

1.21 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: 6dd12fd2f105ee082a80590b030cc3aa SHA-1: 01ba2c2e4cebb689006105733ac81a3f5b8525ee SHA-256: 2da8790cff57665b3725ad45e7077381427caae6f0eac4e19768d7960693112b
170 Risk Score

Malware Insights

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

The critical ClamAV detection and high-severity heuristics for OLE Equation Editor objects strongly indicate exploitation of the Equation Editor vulnerability. The presence of an anomalous Ole10Native stream within the Equation Editor object suggests it carries a malicious payload. The file is identified as a downloader, likely leveraging the embedded OLE object to fetch 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.
  • 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://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/tiff/1.0/

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
3fcb04838f18d27e75d29126d65e0a8fd6ce61798d90baead3710128630258c7		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 906752 bytes
ooxml_oleobject_00_ole10native_00.bin
9f0eb60c4453c087d30900d36f2fc3df7031e824ee850d2cf391f1d7727d4fc7		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OLE10NaTIVE 897338 bytes
ooxml_oleobject_01.bin
48757ea561560bb1d06852212b15d0a46b40e5ba18557a2fa30a2e45ce294797		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject2.bin 32768 bytes
ooxml_oleobject_01_ole10native_00.bin
d99c4f7b75c5d87127e2729121a439c1a52b946b0accab53494d8313bb27bd81		 ole-package OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native 30925 bytes
emf_00.emf
8bdc5f76cc53448d40adeb12710252a11e99ee96ec4671b8c9d5fbb1bc08e39d		 ooxml-emf OOXML EMF part: xl/media/image5.emf 648132 bytes
emf_01.emf
d1c1bcd9355fdcddf1e23c28902bb41d13b48f64898bf4c4aac1221bd7e33aa8		 ooxml-emf OOXML EMF part: xl/media/image6.emf 7592 bytes

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