Office (OOXML) / .XLSX malware analysis — malicious · 52d303dc0f45b89c

MALICIOUS

Office (OOXML) / .XLSX

1.07 MB Created: 2010-08-19 07:36:00 UTC Authoring application: Microsoft Excel 15.0300

MD5: 642de9034b6f457eaeaa9a190c0bdd4b SHA-1: e357a509180945884f181d0fcea045b42bffc807 SHA-256: 52d303dc0f45b89cc7440e6be75b4e57c53ebca7404f65ba2da7062bbe37f0b2

190 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious Link

The file is an OOXML document containing an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object is anomalous and carries a payload-like stream, exploiting CVE-2018-0798. The document body presents as a commercial invoice, a common lure for advance-fee scams. No scripts were extracted, but the presence of the malicious OLE object strongly suggests the intent to deliver a secondary payload, likely for financial fraud.

Heuristics 7

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/ApFF7n3u8.U5Ro 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.
Advance-fee lottery/parcel scam lure high SE_ADVANCE_FEE_SCAM_LURE

Document contains lottery/beneficiary or prize language together with large-value draft/funds wording and parcel/courier delivery requirements. This is a classic advance-fee fraud document shape.
Embedded OLE object medium OOXML_OLE_OBJECT

Document contains an embedded OLE object
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
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` `71c8d1a799e0ec765da89ef77610a889fb05a9292e2e1b415b6ed1a8ae9c84cb`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/ApFF7n3u8.U5Ro	1358336 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.83, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `d99a85b2daa2c5ffb6d75b52851d87690a76e7b4f9df3c5e5fcb4a723ff1d22f`	ole-package	OOXML xl/embeddings/ApFF7n3u8.U5Ro Ole10Native stream: oLe10NaTIve	1345498 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.73, consistent with packed or encrypted content.

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