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

Static analysis result for SHA-256 1f7f0e807662dea1…

MALICIOUS

Office (OOXML) / .XLSX

222.7 KB Created: 2006-09-16 00:00:00 UTC Authoring application: Microsoft Excel 12.0000
MD5: 227b81ccaf9798b0d5b15756a9fab2d2 SHA-1: ad677e3605710f247d61aaa81cbf46a482afb60f SHA-256: 1f7f0e807662dea1f41db59b70e82b89dee30c7f08a920ee2004273a5de977e3
108 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. Heuristics indicate this object is anomalous and exploits CVE-2018-0798, a vulnerability in Equation Editor that allows for arbitrary code execution. The presence of a hidden sheet further suggests an attempt to conceal malicious content. No specific malware family could be identified, and no further IOCs were extracted.

Heuristics 4

  • 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
  • Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
a70759640380e4965ae609f005267b7479c10ca1a3a3d58574e3edb6d500e569		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/oleObject1.bin 4096 bytes
ooxml_oleobject_00_ole10native_00.bin
e7e84fbb0dd8f16417ab090376e02dd144e2fcc12193a3088667b0769d83f8fb		 ole-package OOXML xl/embeddings/oleObject1.bin Ole10Native stream: oLe10naTIVE 1714 bytes
emf_00.emf
2d04dde3315560cde6701c791e672d08f4842ebbaa56673214e29a6e0e85b17c		 ooxml-emf OOXML EMF part: xl/media/image8.emf 498420 bytes

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