Office (OOXML) / .XLSX malware analysis — malicious · 870c31aa344b2950

MALICIOUS

Office (OOXML) / .XLSX

1.52 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-04-25

MD5: d1177ffcb48aeb76822dc94fbba533f9 SHA-1: 211966d5667c154ab49ff9660364eeb7f049ea53 SHA-256: 870c31aa344b2950d0ea4849a472dafed312ecee8aa212c47bf543668bbee8e9

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Office Open XML (OOXML) file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object is anomalous and carries a payload-like Ole10Native stream, strongly suggesting exploitation of CVE-2018-0798. This technique is commonly used to deliver second-stage malware. No scripts were extracted, but the presence of the vulnerable OLE object is sufficient evidence of the attack pattern.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/yrjRW3nV.r5eQBO 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` `aa1d1d5331cc10dbc5351f542766893b2dbcb81c7b9f5600c8391d00428068a8`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/yrjRW3nV.r5eQBO	1856000 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` `e08dd154ab09bee7c3d35282582db8566007a05d749017a0c9a5612c1b1aae6e`	ole-package	OOXML xl/embeddings/yrjRW3nV.r5eQBO Ole10Native stream: Ole10Native	1838998 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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