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

Static analysis result for SHA-256 41d4baaa5dc08a18…

MALICIOUS

Office (OOXML) / .XLSX

829.8 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-05-17
MD5: 7a839bb53cfd63dfd37b2080b0b1caa2 SHA-1: e1b2d967ce592b550d525464f98de56a25faa651 SHA-256: 41d4baaa5dc08a1833322188545f86f4c3924cacce6c4fba9113826075cfb739
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: DLL Side-Loading

The critical ClamAV detection and high-severity heuristics indicate the presence of a malicious OLE object, specifically an Equation Editor exploit. This exploit likely leverages a vulnerability to download and execute a secondary payload, as suggested by the 'Downloader.Trojan' classification. The embedded OLE object and its anomalous Ole10Native stream are key indicators of this attack vector.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/6Lz4FCq.uS 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
b1c6361d0b869c163738bc36c7fe65d4e874bb89e3fd3c6d67f3d0eafa26a89b		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/6Lz4FCq.uS 994816 bytes
ooxml_oleobject_00_ole10native_00.bin
c54854ea4d8588b852574fe3a8fbb154eb8c57cadf292b67507c49131e719889		 ole-package OOXML xl/embeddings/6Lz4FCq.uS Ole10Native stream: OLe10NaTive 984557 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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