Office (OOXML) / .XLSX malware analysis — malicious · 88f2688c1d5405bb

MALICIOUS

Office (OOXML) / .XLSX

764.5 KB Created: 2020-03-17 04:10:45 UTC Authoring application: Microsoft Excel 12.0000

MD5: fbe979170054fe0274f6332aace920b3 SHA-1: f25b1eadf7f7f84df62a74a2a220db49445f9855 SHA-256: 88f2688c1d5405bb3ebac4098042dde3a79b2c2e10b026df3a3f797496a70c22

100 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel file containing an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous header, strongly suggesting it's being used to exploit a vulnerability. The high entropy of the stream further supports the presence of packed or encrypted malicious code. No document body or scripts were provided, so the exact nature of the payload cannot be determined, but the exploit vector is clear.

Heuristics 3

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/wqgxP73Q.fZdqxb 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `aba5a9ec7a2e5b124f1171c3a9a084c33c63ed047364c3185cae93c6e500b963`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/wqgxP73Q.fZdqxb	1010176 bytes
`ooxml_oleobject_00_ole10native_00.bin` `943486996dbacfffb16ddb7b0bcfbdf9c27562d7cc6b53bc13f177e0b78c076e`	ole-package	OOXML xl/embeddings/wqgxP73Q.fZdqxb Ole10Native stream: ole10nAtive	999797 bytes

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