Office (OOXML) / .XLSX malware analysis — malicious · a2efe311a9028a59

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 37e737e56fe55aec5e0c02b05a9bef0a SHA-1: 6bba5c860cba1856a354f745178c963bb215fcf4 SHA-256: a2efe311a9028a59c32c4d2042ac3b826586358abda17103eb77208be7036eeb

142 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1566 Phishing T1566.001 Phishing: Spearphishing Attachment

The file is an Office document containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate this object exploits CVE-2018-0798 due to anomalous native stream properties and high entropy, suggesting it carries a malicious payload. The document body contains what appears to be a parts list, likely a lure to disguise the malicious nature of the embedded exploit. The embedded OLE object and its anomalous native stream are the primary indicators of compromise.

Heuristics 5

Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR

Embedded OLE object xl/embeddings/oleObject1.bin 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` `9b9c7d231e1b1bcf0199ef72aa1d5edfe363944127b2a84e65824814e1c585c0`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	364544 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `efaa552821b195c961628473282bd4522ea3baffd4d07061b24b31d898e2879b`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: Ole10NAtiVE	359105 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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