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

Static analysis result for SHA-256 c098030dd08bc986…

MALICIOUS

Office (OOXML) / .XLSX

797.0 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-03-10
MD5: 1bb401b0802a85eaa6c64f636772cc3c SHA-1: efa7a7b3e412f483e8b901f0f6375197b87a0ce3 SHA-256: c098030dd08bc9866d5fadc143a4cff0f26d1a72522a55e27e55b9bf27afa0f9
160 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel file containing an embedded OLE object, specifically identified as an Equation Editor object. Heuristics indicate that this object carries a payload-like Ole10Native stream with an anomalous header and size discrepancy, strongly suggesting exploitation. ClamAV detection confirms this as a downloader trojan. The embedded OLE object is the primary vector for delivering the malicious payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/QdXvMTK.KHw 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
f37cffb517ba13b092323e87d30390b0d118cd84a6542191b4e99eb57bb68c5b		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/QdXvMTK.KHw 908800 bytes
ooxml_oleobject_00_ole10native_00.bin
544f3b3cf74d3b4b51699aa901c4ab7fe75b1a455945227e64cbc68553e45dbc		 ole-package OOXML xl/embeddings/QdXvMTK.KHw Ole10Native stream: oLe10naTIve 899401 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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