Office (OOXML) / .XLSX malware analysis — malicious · fce896d93c20c1ce

MALICIOUS

Office (OOXML) / .XLSX

1.27 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-18

MD5: 731895eeaf37d14f2d34d083e9f6bdae SHA-1: 10abee02f46b0b1badb330564464a8e8f11b1b7c SHA-256: fce896d93c20c1ce234ded51b934d74f7478df9d9afca628f9f309a902b50b20

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an OOXML file containing an embedded OLE object, specifically identified as a vulnerable Equation Editor object. Heuristics indicate that this object carries a payload-like Ole10Native stream, exploiting CVE-2018-0798. This suggests the file is designed to leverage this vulnerability to execute a secondary payload upon opening. No VBA or scripts were extracted, but the presence of the exploit is sufficient evidence of malicious intent.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/Bifu.CgeR 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` `8ba15f68486e128206b520afe6c3bdf1d3d8e1d1add2d3b604ae10e0280983a5`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/Bifu.CgeR	1625600 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` `920566fabd6624489df0980f02832294276f60501eb592084cece96336711fd1`	ole-package	OOXML xl/embeddings/Bifu.CgeR Ole10Native stream: Ole10Native	1610329 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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