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

Static analysis result for SHA-256 8a7fdf431ee50660…

MALICIOUS

Office (OOXML) / .XLSX

860.2 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-07-18
MD5: ee8e198bbfa8155a84a12dc412461939 SHA-1: 63d5ed2c2241564e3f6c860887a3c652c1fdf472 SHA-256: 8a7fdf431ee50660c8846ead9cd6ca2e7f9855e2ec150565f0e336f778c8418d
160 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1566 Phishing T1059 Command and Scripting Interpreter

The sample is an Excel file containing an embedded OLE object, specifically an Equation Editor object. This object exhibits anomalies in its Ole10Native stream, suggesting it carries a payload. ClamAV detection confirms this as a downloader trojan. The presence of these indicators strongly suggests the file is designed to download and execute a secondary malicious payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/1v4DOlr7B.Ibabam 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
545149348205ee8e6558f814b5204a0b850bb6725fa4aa61d5274daf8a84f256		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/1v4DOlr7B.Ibabam 1015808 bytes
ooxml_oleobject_00_ole10native_00.bin
75dacc74a8fae0c3adf5572a92a72df40bf190e81e007d92c1192f0bec1374ed		 ole-package OOXML xl/embeddings/1v4DOlr7B.Ibabam Ole10Native stream: ole10nAtIve 1005393 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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