Office (OOXML) / .XLSX malware analysis — malicious · 33107fe6b1d208fb

MALICIOUS

Office (OOXML) / .XLSX

1.65 MB Created: 1996-10-14 23:33:28 UTC Authoring application: Microsoft Excel 15.0300

MD5: a6cdf6696a8be194e707b390abbbc651 SHA-1: 597e13556b62c033ea57e6c83a2f0629a60b37d1 SHA-256: 33107fe6b1d208fbde2e04b43e488c2bef4429f1c5634097f240fb18682fbfa7

162 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1059.005 Visual Basic

The file is an Excel spreadsheet containing an embedded Equation Editor OLE object, which is anomalous and indicative of malicious intent. Heuristics indicate that this object carries a payload-like stream, potentially exploiting CVE-2018-0798. The document body contains a lure instructing the user to 'ENABLE EDITING', a common tactic to bypass macro security and execute embedded malicious content. The embedded OLE object is the primary indicator of compromise.

Heuristics 6

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/Lfg5A0TWf.FkZ 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
Macro/content-enable lure medium SE_ENABLE_LURE

Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings
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` `76b6984d44d13b0459009465237b96f266ae858a3f29b8eb40adad4a2a1b6b8e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Lfg5A0TWf.FkZ	1949696 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` `4b151273d1075fb50a22fd5d6911b04245ba661e34dd306319077f93b804348e`	ole-package	OOXML xl/embeddings/Lfg5A0TWf.FkZ Ole10Native stream: oLe10NatiVe	1932053 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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