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

Static analysis result for SHA-256 8176fd33d34027a8…

MALICIOUS

Office (OOXML) / .XLSX

2.01 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: bf98fab307607123b39fc838bbbf7e23 SHA-1: 2d596c3419b1a6b93b14078bf7501c7335c5decf SHA-256: 8176fd33d34027a8182088bd77db573192c401799e09b4251482d83b954adfc8
154 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an Excel spreadsheet containing an embedded Equation Editor OLE object. High-entropy anomalies within the OLE object's native stream strongly indicate exploitation of CVE-2018-0798. This object contains a URL, http://www.day.com/dam/1.0, which is likely used to download and execute a second-stage payload. The presence of a hidden sheet further suggests an attempt to conceal malicious activity.

Heuristics 8

  • 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
  • Payload URL recovered from embedded OLE object (1 URL) info OOXML_EMBEDDED_OBJECT_URL
    An embedded OLE object (xl/word/ppt embeddings) carries a next-stage download URL in its Ole10Native/Package stream — stored literally (incl. UTF-16) or base64-encoded — which the package-level URL sweep does not see. Surfaced as an IOC; self-validating (only real payload hosts).
  • 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.
  • 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 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
a7c19e6406b0f06cbc09bff72a26846618608c6a5e6f9cc665c852a7cde58d59		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 1622528 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.
ooxml_oleobject_00_ole10native_00.bin
06660469856eab4c4df52e122477430c83701aba3e6d6a08e7d3072079a6cf60		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OLE10NatIVE 1607335 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.99, consistent with packed or encrypted content.
ooxml_oleobject_01.bin
08fa0762988438995438654ceb1363b322e0964042bf55fa427c1a2172e1bd54		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/Microsoft_Office_Word_Macro-Enabled_Document1.docm 127546 bytes
emf_00.emf
c1665a92094dac9541f8525a83934e7f9e42b767b9a031dbb45c43c5403dbc08		 ooxml-emf OOXML EMF part: xl/media/image10.emf 653280 bytes

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