Office (OOXML) / .XLSX malware analysis — malicious · 72d65a46db11b7a6

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 9a505aa432f17d55944c1944a6cae852 SHA-1: 24a736db9d30200dc03287111f5912b3ff1d8a03 SHA-256: 72d65a46db11b7a68aeb3726da3317233f8e92b7c64271c85c5e717029f0fafb

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an Excel document containing an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate this object exploits CVE-2018-0798, a known vulnerability in Equation Editor, and carries a suspicious Ole10Native stream. This suggests the file is designed to execute arbitrary code upon opening, likely as a spearphishing attachment.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/s9K2iwPng.TTKqxn 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` `c647fa6f4c1e95c6644f516d6a4f4118744d352d080bb81e963c5e3290572e17`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/s9K2iwPng.TTKqxn	1488896 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` `fb32fffafcc8bca43e48ab2a7ca7b5b7668bf423e07528f8f8f103c06cad9664`	ole-package	OOXML xl/embeddings/s9K2iwPng.TTKqxn Ole10Native stream: Ole10Native	1474662 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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