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

Static analysis result for SHA-256 13539480905e4d35…

MALICIOUS

Office (OOXML) / .XLSX

657.6 KB Created: 2021-04-28 21:02:36 UTC Authoring application: Microsoft Excel 12.0000
MD5: 1429c31643936e2a9681c265d7c66542 SHA-1: c47b77622f2fd95551d210e53ca24f982cc5c3c2 SHA-256: 13539480905e4d35d2437d149610838248f8fe14741a5f913b1171bb4d2da5b3
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is a malicious Excel file containing an embedded OLE object that exploits CVE-2018-0798 via Microsoft Equation Editor. This vulnerability allows for the execution of arbitrary code, likely to download and run a secondary payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/er7MYMC.YVW 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
77256d598d4578c336a9c9197b8549f0e21d0a819198fb0a7649d9b34c86df24		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/er7MYMC.YVW 972288 bytes
ooxml_oleobject_00_ole10native_00.bin
8dc705464dc6b9b6c13b5b235e7b2e60f43be1890accdcccf390c738da129867		 ole-package OOXML xl/embeddings/er7MYMC.YVW Ole10Native stream: Ole10Native 962433 bytes

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