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

Static analysis result for SHA-256 798ca3d1ca400865…

MALICIOUS

Office (OOXML) / .XLSX

724.5 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-07-18
MD5: fd17d5e1f7778cbc8fa1188ac7da59fa SHA-1: 86eed63139190762010f7270daf63a9f52c03f18 SHA-256: 798ca3d1ca400865fbef12dd12e057b3000eb86a4ce9393360e5573039e5ee74
160 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1204.002 Malicious File

The sample is an Excel file containing an embedded OLE object, specifically identified as a Microsoft Equation Editor object. High-severity heuristics indicate that this Equation Editor object carries a payload-like Ole10Native stream with an anomalous size difference, strongly suggesting exploitation of a vulnerability like CVE-2017-11882. 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/gF.WGx6B 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
2dc6715ebd49a1aff529dcb405ea10304956af110fbe355a532a1ae45baf6842		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/gF.WGx6B 802304 bytes
ooxml_oleobject_00_ole10native_00.bin
79898debb902b29eb572b6801737fcc38e84b4858028b45ea7d12fd87b0ff120		 ole-package OOXML xl/embeddings/gF.WGx6B Ole10Native stream: oLE10nAtiVE 793246 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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