Xls.Downloader.Trojan-aa0b8f388d8573cd — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 51790b07b6931f56…

MALICIOUS

Office (OOXML) / .XLSX

804.4 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-05-18
MD5: 8431facee7e432563d2ed43fd85e75a2 SHA-1: 6aab7daeb8a3682d3c8190f3a0a62644d17b258f SHA-256: 51790b07b6931f5681edd341f04315b90034198c61ee1c7d1d80f4df6f06d300
160 Risk Score

Malware Insights

Xls.Downloader.Trojan-aa0b8f388d8573cd · confidence 95%

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

The file is identified as a malicious Excel document by ClamAV, specifically as 'Xls.Downloader.Trojan-aa0b8f388d8573cd'. Heuristics indicate the presence of an embedded OLE object, specifically an Equation Editor object, which carries a payload-like stream with an anomalous header. This suggests the object is designed to exploit a vulnerability or execute malicious code upon interaction, likely serving as a downloader for further malicious activity.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/napB1JlJ6.zvk 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
6a903f1004bee98882216624ada5d7b81902cb46b9976322b1271d3df31c557b		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/napB1JlJ6.zvk 936448 bytes
ooxml_oleobject_00_ole10native_00.bin
636ccf0bd9b5ef5f94cf269d3993748f6ec049ad690d07ca55d93f8fa79353ce		 ole-package OOXML xl/embeddings/napB1JlJ6.zvk Ole10Native stream: ole10naTiVE 926299 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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