Office (OOXML) / .XLSM malware analysis — malicious · 18c3c2bb0dcecfc3

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: 0b3a67ed4345f9a78699d1cf94d97ca1 SHA-1: 934f6af23ca3ed74c3ed258d4f1a7a519d7c1656 SHA-256: 18c3c2bb0dcecfc36f0604781b1f2bc587995eb2ef00c4dbd7871d06e167db01

210 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The sample is an XLSM file containing Excel 4.0 macros. These macros utilize dangerous functions like FOPEN, FWRITE, FCLOSE, and EXEC to write and execute a second-stage payload. The DOC BODY indicates the payload is likely located at C:\ProgramData\zberuzfPH.sct, which is then executed by the macro.

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` `f4a885907dd019bbeb0b7e016b62337a64170d25968f6a09d362308b0da1aec8`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	991367 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 shell/COM execution token(s).

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