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

Static analysis result for SHA-256 534526d26d379833…

MALICIOUS

Office (OOXML) / .XLSX

743.6 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2024-06-24
MD5: 24bd7a0abc542cf4e83e520afb294d51 SHA-1: e1835692723742859142c9f3d22f6b928e397dae SHA-256: 534526d26d379833d53e962215799e35aa4e20e4c0b6f8eee96b3aa69ba4494b
160 Risk Score

Malware Insights

Xls.Downloader.Trojan-aa0b8f388d8573cd · 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, indicating it carries a payload. ClamAV detection confirms this as a downloader trojan. The presence of an embedded OLE object, particularly one with a payload anomaly, strongly suggests a malicious intent to deliver a secondary stage.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/EVkK.ne 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
ab0a6e41632e772fa18020d82cc1b37fb1f737fbeb0c8c590ba91afa8be57457		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/EVkK.ne 883712 bytes
ooxml_oleobject_00_ole10native_00.bin
03a8d203c3a9f988212cf43a6aad42309b5bd3accc6c2212e39020ae5cfd73e9		 ole-package OOXML xl/embeddings/EVkK.ne Ole10Native stream: OLE10natiVe 874169 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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