Office (OOXML) / .XLSM malware analysis — malicious · e00e4ae741e549cd

MALICIOUS

Office (OOXML) / .XLSM

113.0 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 32e3d3ebeccd3df67c9a1ceb55e771db SHA-1: cb04ecfc317604536d101d00b05a20f84d5e36ab SHA-256: e00e4ae741e549cdec85c6ebde1df9b94bfbd179b49028ea3abe6e9d529f74da

130 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Control T1059.001 PowerShell: PowerShell T1204.002 Malicious File: User Execution T1059.003 Command and Scripting Interpreter: Windows Command Shell

This Excel 4.0 macro sheet utilizes dangerous functions like FOPEN, FWRITE, and EXEC to download and execute a payload. The script reconstructs the path 'C:\ProgramData\HUcaiR\kJ.vbs' for writing the payload and uses an ALERT function to display a deceptive message to the user. The use of these functions indicates a clear intent to execute a second-stage payload.

Heuristics 4

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.
Dangerous XLM formula APIs: FOPEN, FWRITE, FCLOSE, EXEC, RETURN 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.
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` `4cee5f840302fd4cf4ffee70a032ca4893ae69e8b081c1c59538a3bb5b29e514`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	5723 bytes

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