Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0 — Office (OOXML) / .XLSX malware analysis

Static analysis result for SHA-256 58cae727981e32c5…

MALICIOUS

Office (OOXML) / .XLSX

865.7 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-08-09
MD5: 81b5a219d9a0f57076558bfe5a0a843e SHA-1: 81317dccebb31fe6108679059620f3c0d2f58329 SHA-256: 58cae727981e32c5d836888f1cf5c64dcc43109e830db94cef4254770e36f83e
160 Risk Score

Malware Insights

Xls.Downloader.Trojan-aa0b8f388d8573cd-aa0b8f388d8573cd-9950439-0 · confidence 95%

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

The file is an Excel document containing a high-risk OLE object, identified as an Equation Editor exploit. This exploit carries a payload within its Ole10Native stream, indicated by anomalous stream size and entropy. ClamAV detection confirms this as a downloader trojan, likely executing a second-stage payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/MFoMDezyE.kfOHAjU 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
be33b755e1b5aea5878b89614dd766a44ac1df2c47b7f5ae80630f170092de4f		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/MFoMDezyE.kfOHAjU 1029632 bytes
ooxml_oleobject_00_ole10native_00.bin
849d303eb3ec35754be8fd9cdc6d1b560b84afa2a38c176eada7bcabbfac1b26		 ole-package OOXML xl/embeddings/MFoMDezyE.kfOHAjU Ole10Native stream: OLE10NAtIVe 1019314 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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