Xls.Downloader.Trojan — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 6f0702bd1067a59d…

MALICIOUS

Office (OOXML) / .XLSX

824.2 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-08-16
MD5: c3b806165bc819983038bbf4a9678195 SHA-1: 95d8b970434ec336140735a9784742032a4710ec SHA-256: 6f0702bd1067a59dc036e671bc71f3ace69ed18c1e765baf515ec71c024fce7f
160 Risk Score

Malware Insights

Xls.Downloader.Trojan · confidence 95%

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

The sample is an Excel file containing an embedded OLE object, identified as an Equation Editor object. This object exhibits anomalies in its Ole10Native stream size and entropy, strongly suggesting it carries a malicious payload. ClamAV detection confirms this, classifying it as Xls.Downloader.Trojan.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/aU2WuhBz0.j32a9 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
78c6534496b54dd4b0a8db527863be22a531de9104ee743f86be8019e7d31073		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/aU2WuhBz0.j32a9 1020928 bytes
ooxml_oleobject_00_ole10native_00.bin
50265edb464dfdba3da41156efca0e9be08b49541575e729c7370b43245695fb		 ole-package OOXML xl/embeddings/aU2WuhBz0.j32a9 Ole10Native stream: OLE10nATIVE 1010525 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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