Office (OOXML) / .XLSX malware analysis — malicious · a6af0911fde693a4

MALICIOUS

Office (OOXML) / .XLSX

1.68 MB Created: 2019-10-24 08:51:40 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-02-18

MD5: 1753378504820140c698db7c025e09c4 SHA-1: 0938bf21212401ac11ae8974132d14053f32baa1 SHA-256: a6af0911fde693a4d5a674fd5a9936d5b14971ce531ed1029f6c226c543d0f7d

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The file is an Excel spreadsheet containing an embedded OLE object, specifically a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object is anomalous and carries a payload, exploiting CVE-2018-0798. The embedded OLE object and its native stream are identified as suspicious artifacts. The attack pattern involves exploiting this vulnerability to execute a malicious payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/A6B.krggVw 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` `996868cea6100d6ce16314a8d95bf2cc70a46c9443de555de13a72ed5bfa52e1`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/A6B.krggVw	2013696 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` `462586f7ed88c6bc6fb269c30eafcebb15f942d820434f9945f095b3936f8df9`	ole-package	OOXML xl/embeddings/A6B.krggVw Ole10Native stream: oLe10NATiVe	1995714 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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