Office (OOXML) / .XLSX malware analysis — malicious · 324c4b640ed62586

MALICIOUS

Office (OOXML) / .XLSX

1.15 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000

MD5: b84686001b0242c068dd9a5ded84855a SHA-1: d5933c8894c8e739e8e45aad3288d56795d58a2e SHA-256: 324c4b640ed62586462cf36d297eb1787f871c2689959aeba743bff609d8fa84

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel spreadsheet containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded artifact 'xl/embeddings/wS8wk.pHaf' is likely the exploit or the initial stage of the payload delivery.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/wS8wk.pHaf 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
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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `f56a6f8cfb38b7e836e68c17e8aee47dfc8b0271faaca634029753dc67c10b24`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/wS8wk.pHaf	1495040 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.67, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `9a9f9b58b2daff9c72e7ffabc0b3eea2f8426a1e7c9b6e34a57a8fdc5d1c97e8`	ole-package	OOXML xl/embeddings/wS8wk.pHaf Ole10Native stream: Ole10Native	1481078 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.67, consistent with packed or encrypted content.

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