Office (OOXML) / .XLSX malware analysis — malicious · 3a2042b2d6223fd9

MALICIOUS

Office (OOXML) / .XLSX

484.6 KB Created: 2016-12-06 13:03:31 UTC Authoring application: Microsoft Excel 16.0300

MD5: 985547e134d3884d7623d3be63be79b4 SHA-1: f92105f790c1c91697edc79b796d592f4c380c92 SHA-256: 3a2042b2d6223fd9466cfa2d51ba0af56b4df776aa9a2a5af0d05ccf97509792

204 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File: User Execution T1204.001 Malicious Link: User Execution T1071.001 Web Protocols: Web Protocols T1105 Ingress Tool Transfer

The sample is an Office document containing an embedded OLE object, specifically exploiting a vulnerability in the Equation Editor (CVE-2018-0798). The embedded Ole10Native stream contains shellcode that uses WinAPI functions like URLDownloadToFileW and WinExec to download and execute a payload from the URL http://membranehartebeest.org/v/A59xKtY2T8jNDEt.exe. This indicates a downloader attack pattern.

Heuristics 7

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 Ole10Native downloader shellcode critical OLE_EQUATION_OLE10NATIVE_DOWNLOADER

Embedded OLE object declares the Equation Editor CLSID and its Ole10Native stream contains downloader shellcode API strings plus a remote URL. This is high-confidence exploit payload evidence, but it is not assigned to a specific Equation Editor CVE without a matching malformed MTEF/Equation Native primitive.

URL http://membranehartebeest.org/v/A59xKtY2T8jNDEt.exe
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.
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — context-specific rules above attribute URLs they actually evaluated; this rule lists URLs that were present in the bytes but were not otherwise tied to a specific finding.
URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
- http://schemas.openxmlformats.org/officeDocument/2006/relationships
- http://schemas.openxmlformats.org/markup-compatibility/2006
- http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac
- http://schemas.microsoft.com/office/spreadsheetml/2014/revision
- http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
- http://schemas.microsoft.com/office/spreadsheetml/2016/revision3

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`ooxml_oleobject_00.bin` `fe098aa933a7b6a4895779334f0fda617cccf5da96c903258dc9edf3bcd8d0af`	ooxml-ole-object	OOXML embedded OLE part: xl/embeddings/oleObject1.bin	460800 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.
`ooxml_oleobject_00_ole10native_00.bin` `dd2c5dc483dc6dd232fed29a0f39ad285308843aa50e467422c14b98e5e1567f`	ole-package	OOXML xl/embeddings/oleObject1.bin Ole10Native stream: oLe10nATIvE	454299 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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