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

Static analysis result for SHA-256 35a544f14c330e04…

MALICIOUS

Office (OOXML) / .XLSX

848.7 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-02-10
MD5: 42dd716f9dd2ef53845241c1fb19a964 SHA-1: 4322309d53c2c2733f89c0c423e3285bdd68aa88 SHA-256: 35a544f14c330e044881714df26e592cd245e0d88805e566ca07b5253aed34b7
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1559 Component Object Model Hijacking

The file is identified as malicious by ClamAV as a downloader trojan. Static analysis revealed an embedded OLE object within an Equation Editor component, which is a known exploitation vector. The anomaly in the Ole10Native stream size suggests it contains a malicious payload, likely executed upon opening the document.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/wtZOzzn.uJtDjdj 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
a950692fce5fe890b8e068078615e406ea6403d2ec6b584119edc04f3dedf9ca		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/wtZOzzn.uJtDjdj 1063936 bytes
ooxml_oleobject_00_ole10native_00.bin
17f669b8c29dd962b765367a7cefcd524d7cfa63fdd159991d00379a24b5edad		 ole-package OOXML xl/embeddings/wtZOzzn.uJtDjdj Ole10Native stream: Ole10NATIvE 1052984 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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