Office (OOXML) / .XLSM malware analysis — malicious · 7d757b58bd392703

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: 1054fad344069eccdc8a91281a349d46 SHA-1: 22b851af38bb40b3ea44df57d06bffa0bbc92224 SHA-256: 7d757b58bd3927035571e0212a119aec5a4cb868c5d40f8a13d3102d55bb7929

130 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an XLSM document containing Excel 4.0 macros. These macros utilize dangerous functions like FOPEN, FWRITE, FCLOSE, and EXEC to construct and execute a VBScript file named 'HdYoK.vbs' in the 'C:\ProgramData\' directory. The script is likely a downloader for a second-stage payload, indicated by the use of these functions and the overall malicious verdict.

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` `e6fbae5825ef23f7f89f3f012a6001b4271347d7440434ae0ae67660f7e77432`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	5383 bytes

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