Office (OOXML) / .XLSX malware analysis — malicious · 5c8868a67798f2d7

MALICIOUS

Office (OOXML) / .XLSX

2.38 MB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000

MD5: bf1f9bd058413cbd3b287a14e7c1dd91 SHA-1: 7e87982a148a1be25a5213c853e3aff528eda08f SHA-256: 5c8868a67798f2d72ed1415194fd3b2f32c8faef8fa3c2851d4bf2fdd3e41b5b

152 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample contains an embedded Equation Editor OLE object with anomalies in its native stream, indicative of CVE-2018-0798. This exploit typically leads to the execution of a second-stage payload, likely downloaded from a remote source. The presence of a hidden worksheet also suggests an attempt to conceal malicious content.

Heuristics 7

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.
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.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `d57e334e0ddd99b269fce66dcd8acb6b10861e94d97b8e0835d3ecad4d89e9a9`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	1923072 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` `964233f88a80e93ccc4a2ac5856f26afdde9e99f48dadb688eaf49cd54b2c724`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: ole10NATive	1905458 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` `2829fb59a81b41814ab720cb87f5360eaa59900487e9cdbb814a17fcbd997399`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Microsoft_Office_Word_Macro-Enabled_Document1.docm	127545 bytes
`emf_00.emf` `83897ae4e1b877e16e2e09cdf6270c1b7d6effa657102bc32dabb89f21d7ab06`	ooxml-emf	OOXML EMF part: xl/media/image7.emf	653280 bytes

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