Office (OOXML) / .XLSX malware analysis — malicious · bea56a0f5a371dac

MALICIOUS

Office (OOXML) / .XLSX

1.28 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-06-03

MD5: 5894a500c9eb45a7400fef2a2c175e75 SHA-1: 07f55bbba6ea14025974149596d061a0294ec50e SHA-256: bea56a0f5a371dacc6d0e11db1ed4a9a422dd2a42e316252d2ebfbd727026542

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model

The sample is an Office Open XML spreadsheet containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this object is anomalous and carries a payload, strongly suggesting exploitation of CVE-2018-0798. The embedded OLE object's native stream is highly entropic and oversized, consistent with a packed or obfuscated second-stage payload. No VBA macros or document body text were extracted, but the presence of the vulnerable Equation Editor component is sufficient to infer the attack pattern.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/C3C.ieJ 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` `7f2c9d86aac36f23ba9b578b4d9d758da27a3f69727614a059618de8a263942f`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/C3C.ieJ	1553408 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `fb42b103407326e321a45a0884d2ba3699129a794e1d02651a6cfdca050e6bce`	ole-package	OOXML xl/embeddings/C3C.ieJ Ole10Native stream: olE10naTiVe	1538896 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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