Office (OOXML) / .XLSX malware analysis — malicious · 48c2dca85b8198eb

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 553dbe499387cacae8ec4be3fa5dc22a SHA-1: e71a076653947227c1488da7e06e8d68d0ca31c0 SHA-256: 48c2dca85b8198eb46cc23467836af27b36f3f42e0dce4a8a3c541860ec708c9

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1204.001 Malicious Link: Malicious File T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter

The file is an Office Open XML (XLSX) document 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 a second-stage payload. No scripts were extracted, and no document body was available for analysis.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/UDC.CtyuYR 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` `d800f1ff20240573107875912a948b073cda8a0b4f2f25ddfa1cf9420856283c`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/UDC.CtyuYR	2092032 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` `90abc0fc7a5b7571463df2f8af2c5cd93a3ec614383077cd23f2494e537fa4b6`	ole-package	OOXML xl/embeddings/UDC.CtyuYR Ole10Native stream: oLE10natiVe	2073399 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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