Office (OOXML) / .XLSX malware analysis — malicious · 3b85e0df48291de8

MALICIOUS

Office (OOXML) / .XLSX

698.9 KB Created: 2019-11-27 09:20:57 UTC Authoring application: Microsoft Excel 12.0000

MD5: ffc4e1c4be655ce634a50540f921cc9e SHA-1: 1aeb0b44d135465d549acf222e867e34913aaeb5 SHA-256: 3b85e0df48291de8daaad23256b9313b443e0c896471572660d48c42df1472cb

100 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Phishing: Spearphishing Attachment T1204.002 Malicious File: Malicious File

The sample is an Office document containing an embedded OLE object, identified as an Equation Editor. Heuristics indicate that this object carries a payload-like Ole10Native stream with an anomalous header and a significantly larger declared inner size than the actual stream size. This strongly suggests the exploitation of a vulnerability within the Equation Editor to execute arbitrary code, likely for delivering a secondary payload.

Heuristics 3

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/pxcL.LWj3 contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
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

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `8fed7fb51581c17520eb55ddf7bae2543bb8eb074eb206a3c039f453c1afee3e`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/pxcL.LWj3	976896 bytes
`ooxml_oleobject_00_ole10native_00.bin` `4a2c06f1f152a5d609b80eea7d9e40338e8c82711838af6e69400df51ade6be9`	ole-package	OOXML xl/embeddings/pxcL.LWj3 Ole10Native stream: oLe10NatIve	966985 bytes

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