Office (OOXML) / .XLSM malware analysis — malicious · 7dc116ccdf163ffc

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: 2fcb09820ba15163469dddac3db7e433 SHA-1: e78a787604c3e36b0af2c3cd074f78f679c88fe0 SHA-256: 7dc116ccdf163ffcab2a978619c03943718d1ebe4a80df0d985b53c00d2aca2a

130 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1059.003 Windows Command Shell

The sample is an XLSM file containing Excel 4.0 macros. Heuristics indicate the use of dangerous XLM functions like FOPEN, FWRITE, and EXEC, which are commonly used to download and execute payloads. The reconstructed string 'C:\ProgramData\vidWyGiXorVdn.vbs' from the FOPEN function suggests the creation of a malicious script file. The ALERT function call with 'Error! Sending report to Microsoft...' indicates a social engineering lure. The presence of hidden sheets is also a common tactic to conceal malicious activity.

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` `a9af2734be055d0a20f4c709de6104ff74f07f3e42ac1357a1e77f79af533e82`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	5880 bytes

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