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

Static analysis result for SHA-256 555d5d82bd596542…

MALICIOUS

Office (OOXML) / .XLSX

879.7 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-05-18
MD5: 31ea3fed99e541e410f5d7c145592494 SHA-1: 308697ec6ad9ddd559ee2398f577ad4a03ec6913 SHA-256: 555d5d82bd596542d88df00a74344d09915620f018f49ee0fe13d889717995f7
160 Risk Score

Malware Insights

MITRE ATT&CK
T1559.001 Component Object Model Hijacking T1204.002 Malicious File

The sample is an Excel file containing an embedded Equation Editor OLE object. Heuristics indicate this object carries a payload-like Ole10Native stream with an anomalous size difference, strongly suggesting it's a dropper. ClamAV detection confirms this as a downloader Trojan.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/T9ZC30Yp.3gos 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
81c8a5bd1c0a84a1a6320d221b21a2bba53dc384c97c54ac660f2fc98484c685		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/T9ZC30Yp.3gos 1046016 bytes
ooxml_oleobject_00_ole10native_00.bin
1e76dfba963b19da731a42419445f014bc8b0c2ec936e4e91180ecf87dd8e4fd		 ole-package OOXML xl/embeddings/T9ZC30Yp.3gos Ole10Native stream: Ole10Native 1035497 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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