Office (OOXML) / .XLSX malware analysis — malicious · 6b8c52a0b2922d06

MALICIOUS

Office (OOXML) / .XLSX

1.43 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-16

MD5: 3288bb99c9bf4030e842bef815c64d6e SHA-1: ecdadede627d7b517b0c36247d108192b2f0073d SHA-256: 6b8c52a0b2922d0671e5138938b7a9cc0b79a2c735dc2e4f482e01285ac473a8

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The file is a malicious Excel document containing an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object exploits CVE-2018-0798 by carrying a high-entropy Ole10Native stream, which is likely a second-stage payload. The embedded object's path is also listed as an IOC.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/IGk5u.Ahk1fK 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` `88b9e32dcd5314ae82df42b146f15b0f5ad405e41a982df9501e6ec48d106777`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/IGk5u.Ahk1fK	1798144 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` `72d2ce33ff6cc4eb6b7c6174342e4b02ec7bc833f5a03c02e1d14959da06f3ab`	ole-package	OOXML xl/embeddings/IGk5u.Ahk1fK Ole10Native stream: Ole10Native	1781384 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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