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

Static analysis result for SHA-256 cfda2a790152c5b0…

MALICIOUS

Office (OOXML) / .XLSX

8.9 KB Created: 2021-04-28 14:40:56 UTC Authoring application: Microsoft Excel 15.0300
MD5: 73dbcf2a2e431b3a7ed84228153e900a SHA-1: 0211b11b98033ff523c1a24dd4d9e46ef6d67e74 SHA-256: cfda2a790152c5b0be42dfdefb8ef21faaada6a88f143e1cf996e4a83e9a7237
100 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is an Office Open XML spreadsheet containing an embedded OLE object that triggers a high-severity heuristic for the Equation Editor. This strongly suggests exploitation of CVE-2018-0798, a known vulnerability in Microsoft Equation Editor, which allows for arbitrary code execution. No further IOCs were extracted, but the attack pattern is clear.

Heuristics 3

  • 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.
  • 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
3e2476f5c16d29a03feaf4dc58680271b787b1af1eda4ab7f9c11264f02c4716		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 4096 bytes
ooxml_oleobject_00_ole10native_00.bin
110c02e22ab956857f37d0661d390dcaf0ab7b8d6916d9eac8cfd2484cfd1e7b		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: ole10nAtivE 2006 bytes

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