Office (OOXML) / .XLSX malware analysis — malicious · 4dd84e06b96f5f84

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: cf4c0d89b984ea26bc8aaabaedb67850 SHA-1: 64cf8dde895e3e08d80a659906e2c243c10b38b5 SHA-256: 4dd84e06b96f5f848cd112ac707d2a0b22245da255f69e4bac6179b749c13233

110 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

This XLSX file contains an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous size and entropy, strongly suggesting it's being used to exploit a vulnerability. The presence of hidden worksheets further supports the likelihood of malicious intent, as they are often used to conceal malicious content. The primary attack vector is likely the exploitation of the Equation Editor vulnerability to execute a secondary payload.

Heuristics 5

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.
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.

Extracted artifacts 8

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `1e24d6d3bb7a85d0570588a2610185505ce1971c39f3c2c3a10bfc1e9ed4a0fc`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	964608 bytes
`ooxml_oleobject_00_ole10native_00.bin` `a608be1ab0dbbafa284c04c5fdc441a2fe7e71d75289964a1a6dbe43a52db11e`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: OLE10NaTiVE	954740 bytes
`ooxml_oleobject_01.bin` `e5191d8f29dd9a47668d6d8f46bc84643c80a19c24280b01c3c130c93165f26e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject2.bin	1535488 bytes
`ooxml_oleobject_01_ole10native_00.bin` `f7bfcd2cfafe65360c900b06396fb593106749574e01161bc1df7461e65c0804`	ole-package	OOXML xl/embeddings/oleObject2.bin Ole10Native stream: Ole10Native	1520900 bytes
`ooxml_oleobject_02.bin` `77812feefbdb3c296b819dd72a638f9f1ab565ea3d870a8de8bb62c900ca0907`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject3.bin	29696 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.46, consistent with packed or encrypted content.
`ooxml_oleobject_02_ole10native_00.bin` `d0e65243df358f9ee7948eadb2c9e55da3344dd9a0ee3fcc11d3188c924dc972`	ole-package	OOXML xl/embeddings/oleObject3.bin Ole10Native stream: Ole10Native	28007 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.61, consistent with packed or encrypted content.
`emf_00.emf` `072a6a893b25f4848345ae02773b4dd141c43ec598f34f1da6844dabe6ca8a42`	ooxml-emf	OOXML EMF part: xl/media/image2.emf	3042216 bytes
`emf_01.emf` `23df70071b27afdff609fd8c20b7d34415404c55bb6941fb432f2b396257883a`	ooxml-emf	OOXML EMF part: xl/media/image3.emf	5376 bytes

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