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

Static analysis result for SHA-256 4edf82162fc866d4…

MALICIOUS

Office (OOXML) / .XLSX

878.7 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-04-11
MD5: a5a8e2a8c41e69a0a360f2eac255c77c SHA-1: f8a5c89c428c63e946bc2af34846a4c269825cfd SHA-256: 4edf82162fc866d405ccad0a2613ebda88dfca83b1714b33e4ef56bb105b6195
160 Risk Score

Malware Insights

Xls.Downloader.Trojan · confidence 95%

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

This XLSX file contains a high-risk embedded OLE object identified as an Equation Editor. The object's Ole10Native stream exhibits anomalies, indicating it likely carries a malicious payload. ClamAV detection confirms this, classifying it as Xls.Downloader.Trojan. The presence of these elements strongly suggests a malicious downloader designed to execute further stages of an attack.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/KS.2YMu 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
9985db8ab661db7158e6301fada076b10e7fe1c12e9f0fd3f10136691da550ef		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/KS.2YMu 1018880 bytes
ooxml_oleobject_00_ole10native_00.bin
7c714885d1466f87f3f1e267d8ad8a892efc704e3edb0e9dc9f258a05df463ae		 ole-package OOXML xl/embeddings/KS.2YMu Ole10Native stream: ole10natIVe 1008247 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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