Malicious Office (OOXML) / .XLSX — malware analysis report

Static analysis result for SHA-256 55830ab735afe757…

MALICIOUS

Office (OOXML) / .XLSX

659.2 KB Created: 2021-08-09 02:12:21 UTC Authoring application: Microsoft Excel 12.0000
MD5: a2f16c6db0663942c32fc839f555a2b0 SHA-1: 5ef650ededb53dc918c8543c5ab6d85429504744 SHA-256: 55830ab735afe757af6f61006b1c96bc84ab21d9d3fc376cb2bd4a6db3bc53e0
140 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an OOXML file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object is anomalous and carries a payload-like Ole10Native stream, strongly suggesting exploitation of CVE-2018-0798. This points to a malicious document designed to exploit this vulnerability upon opening.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/6Jsng.yw68W 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

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
ae46cc6d995f2f89847c53d8ebd9f20896eb32c217da590ea0fb931fe6cf9d0d		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/6Jsng.yw68W 965632 bytes
ooxml_oleobject_00_ole10native_00.bin
a1c5b66ff1d7793898a8289e49ed61f508faeed5dd67f67d9f25baa741717766		 ole-package OOXML xl/embeddings/6Jsng.yw68W Ole10Native stream: oLE10nATive 955691 bytes

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