Office (OOXML) / .XLSM malware analysis — malicious · e47802f8f45ef869

MALICIOUS

Office (OOXML) / .XLSM

346.0 KB Created: 2021-08-09 10:17:00 UTC Authoring application: Microsoft Excel 12.0000

MD5: 6115c98bf8ddd72b5e812e4724f1f1b9 SHA-1: 104f876a47f050560a7478143267636373ab4d2f SHA-256: e47802f8f45ef8699743aa5c2e6070787d96a112da6e51f6b192252239a06c38

210 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

This Excel 4.0 macro-enabled document (XLSM) utilizes dangerous functions like FOPEN, FWRITE, FCLOSE, EXEC, and CALL to download and execute a second-stage payload. The presence of these functions, combined with the Auto_Open defined name, strongly suggests a malicious intent to compromise the user's system. The macro sheet itself is large and contains numerous cells with character codes that likely assemble a command or URL for payload retrieval.

Heuristics 6

Excel 4.0 macro sheet (1 sheet(s)) critical OOXML_XLM_MACROSHEET

Spreadsheet contains an Excel 4.0 (XLM) macro sheet — XLM was a major Office malware vector during 2020-2022 and evaded many VBA-focused controls before Microsoft tightened XLM defaults. Even legitimate XLM use is rare in modern workbooks.
Excel 4.0 Auto_Open defined name critical OOXML_XLM_AUTOOPEN_DEFINEDNAME

Workbook defines _xlnm.Auto_Open or _xlnm.Auto_Close while containing an XLM macro sheet. This is the OOXML/XLSB auto-execution shape for Excel 4.0 macros.
Dangerous XLM formula APIs: FOPEN, FWRITE, FCLOSE, EXEC, HALT critical OOXML_XLM_DANGEROUS_FN

Excel 4.0 macro sheet uses formula APIs that call directly into Win32 (=CALL/=EXEC/=REGISTER/=FORMULA). These are the primitives used to download payloads, write files, and start processes from an XLM macro without invoking VBA.
Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 1 hidden sheet(s) — hidden sheets are commonly used to conceal macro code, staging data, or intermediate payload construction
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
URL http://schemas.openxmlformats.org/spreadsheetml/2006/main
- http://schemas.microsoft.com/office/excel/2006/main
- http://schemas.openxmlformats.org/officeDocument/2006/relationships

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `0ae9ca11ed4ef9ffe31a5fb97108cd439499f3aedca63d3057dfd92b165b9ebd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	709288 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).

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