Malicious Office (OOXML) / .XLSM — malware analysis report

Static analysis result for SHA-256 8024e6dc8c230782…

MALICIOUS

Office (OOXML) / .XLSM

146.8 KB Created: 2021-08-26 06:04:04 UTC Authoring application: Microsoft Excel 15.0300
MD5: d1ad5761044b2abb12b78700f1a3a537 SHA-1: 7fed2064ae3681227f674608df64ff1d7c45a2ee SHA-256: 8024e6dc8c230782b570a234318ba7b5a72f64ad5a1a3ff81584e080d9338eba
190 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1204.002 Malicious File: User Execution: Malicious File T1059.001 Command and Scripting Interpreter: PowerShell T1105 Ingress Tool Transfer

This XLSM file contains Excel 4.0 macros that leverage the CALL and HALT functions. The CALL function is used to execute PowerShell, which downloads a second-stage executable from http://212.192.241.75/sam/new3.exe and saves it to the public user directory as eVJOpc.exe before executing it. The HALT function is then called to terminate the macro execution. The use of these dangerous XLM functions and the direct download of an executable strongly indicate a malicious downloader.

Heuristics 5

  • 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: CALL, 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.
  • 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://212.192.241.75/sam/new3.exe
    • http://schemas.openxmlformats.org/spreadsheetml/2006/main
    • http://schemas.microsoft.com/office/excel/2006/main
    • http://schemas.openxmlformats.org/officeDocument/2006/relationships
    • http://schemas.openxmlformats.org/markup-compatibility/2006
    • http://schemas.microsoft.com/office/spreadsheetml/2009/9/ac

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_sheet_00.xml
847bbca933d9318a77ca3f14b3a466602ae795c2f86dbdeb51934b90b1620c0c		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/sheet1.xml 1532 bytes

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