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

Static analysis result for SHA-256 1ce8aaabd9fe827a…

MALICIOUS

Office (OOXML) / .XLSX

878.8 KB Created: 2022-05-16 17:34:45 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2023-03-07
MD5: a1527b5a30d24c1f6f97b913de83b2a0 SHA-1: b96e324b9cad528482253d1efee6a64d810bd4ad SHA-256: 1ce8aaabd9fe827afc2b118a6775bd198f9706604379e35918eac50f51e0d855
160 Risk Score

Malware Insights

Xls.Downloader.Trojan · confidence 95%

MITRE ATT&CK
T1204 Malicious File Execution T1566 Phishing T1204.002 Malicious File Execution: User Execution

The file is an Excel spreadsheet containing an embedded OLE object, specifically identified as a vulnerable Equation Editor object. This object carries a payload-like stream, indicated by an anomalous Ole10Native header and a significantly larger declared inner size than the stream size, suggesting exploitation. ClamAV detection confirms this as a downloader trojan, likely leveraging the Equation Editor vulnerability to execute a secondary payload.

Heuristics 4

  • Equation Editor OLE object high CVE related OLE_EQUATION_EDITOR
    Embedded OLE object xl/embeddings/Hbg.jQt3L 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
d52990e156c31ac9bb09b28e212d4195d8dae50ab998d95bd21c22c2b9fa0436		 ooxml-ole-object OOXML embedded OLE part: xl/embeddings/Hbg.jQt3L 1099264 bytes
ooxml_oleobject_00_ole10native_00.bin
d1da6e0dd8b84a1de2da3445a47fb4f0310ab0f73f68559cb57695d42129b692		 ole-package OOXML xl/embeddings/Hbg.jQt3L Ole10Native stream: ole10nATive 1088461 bytes
emf_00.emf
38f17a599ac5d645df3840bbb401710ef81573a747da20abbfc1b7d9a9273b58		 ooxml-emf OOXML EMF part: xl/media/image1.emf 169096 bytes

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