Office (OOXML) malware analysis — malicious · ef66d0f156c43556

MALICIOUS

Office (OOXML)

889.8 KB Created: 2021-02-03 07:57:22 UTC Authoring application: Microsoft Excel 15.0300

MD5: cd01e052eae016e4577bdc6e004e17f6 SHA-1: a3d26c92635039afe6faf212ec60797a38b25fcb SHA-256: ef66d0f156c43556a6671afda32262704a90d5b038326b88773abbe774c938bb

142 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution

The sample is an Office document containing an embedded OLE object, specifically identified as a vulnerable Equation Editor object. Heuristics indicate exploitation of CVE-2018-0798, suggesting the embedded object is designed to execute a malicious payload when opened. The embedded artifact 'ooxml_oleobject_00_ole10native_00.bin' is likely the payload.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/RHFI1.EZs 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` `bbe4f27ca8557a85fd757e36c2b7a9607b84c9655638b0d68846510434630b97`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/RHFI1.EZs	1165824 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.41, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `bbc309c4d322f71a48891c43f20fce1da3b2b429aac04514301ecaba4423eafe`	ole-package	OOXML xl/embeddings/RHFI1.EZs Ole10Native stream: oLE10NatIVE	1154326 bytes

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