Office (OOXML) / .XLSX malware analysis — malicious · 59df4a1b740a668c

MALICIOUS

Office (OOXML) / .XLSX

1.62 MB Created: 2021-09-22 12:07:42 UTC Authoring application: Microsoft Excel 12.0000 First seen: 2022-03-29

MD5: 08c1da8ba9db5112d19abf36c7887267 SHA-1: 0bc256ae6be8865b49c60427fe2f0218085e1037 SHA-256: 59df4a1b740a668c3fab683f2b19b3178980e01348bc20db0cecc7c076c28b81

142 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel file containing an embedded OLE object, specifically an Equation Editor object. Heuristics indicate this object is anomalous and likely carries a payload, exploiting CVE-2018-0798. The high entropy and size of the Ole10Native stream suggest it contains executable content. No document body or scripts were extracted, but the presence of the vulnerable Equation Editor component strongly points to exploitation for initial execution.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/4RAwMoZH.Zh0 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` `07fd0336bacb1e90ab41828f27f83625fd1c1e7ac1cb7ee87f0c708e70214d8f`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/4RAwMoZH.Zh0	1990656 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` `e3dbf778015898818e5f3fa8710b0bad5cfacf37e00592b0cff4764a1aa70e14`	ole-package	OOXML xl/embeddings/4RAwMoZH.Zh0 Ole10Native stream: Ole10Native	1972368 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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