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

Static analysis result for SHA-256 c05e38425cea2924…

MALICIOUS

Office (OOXML) / .XLSX

873.9 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-06-23
MD5: f3fccc347a973871cfc62392e3fe57cb SHA-1: 8b1a31213379bd2c14491e4e00cf4585b6f7d661 SHA-256: c05e38425cea29244a81d78fe50afe757564eab433436af1c32ea7ae6af4cbf1
160 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking

The critical ClamAV detection and high-severity heuristics indicate this XLSX file is a downloader. Specifically, it contains an embedded OLE object that leverages the Equation Editor, which is a common technique for delivering malicious payloads. The OLE_EQUATION_OLE10NATIVE_PAYLOAD_ANOMALY heuristic suggests the embedded object is designed to execute code.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/VW9vY1x.cGDSK5A contains the Equation Editor CLSID, the legacy component exploited by CVE-2017-11882, CVE-2018-0802, and CVE-2018-0798.
  • ClamAV: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0
  • 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 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
ooxml_oleobject_00.bin
bb0c5543d102247513c889257a5ad8a19cce4b269bbbd932f3884cb7f71caf1d		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/VW9vY1x.cGDSK5A 1100800 bytes
ooxml_oleobject_00_ole10native_00.bin
7f9ac7e3038108b8dc98d334c11a4023374318a726adaeb774b62ed4398fdf97		 ole-package OOXML xl/embeddings/VW9vY1x.cGDSK5A Ole10Native stream: oLE10NaTIVE 1089644 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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