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

Static analysis result for SHA-256 87188912cba10a75…

MALICIOUS

Office (OOXML) / .XLSM

606.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300
MD5: c8766fc5fb2ff8ff1455ebce86926fb7 SHA-1: 8dffc18710fb6e852072b7d06cbf0c23c8fa56d6 SHA-256: 87188912cba10a75e8cdbbb1b6fecb511fc644c85f47548a4b2481ea577f480e
142 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1059.001 PowerShell T1204.002 Malicious File

This XLSM file contains Excel 4.0 macros and a Workbook_Open VBA macro. The Workbook_Open macro attempts to run a subroutine named 'Detio' and then shows a form named 'frmMain'. The Excel 4.0 macros contain strings that reconstruct to a URL 'http://162.248.225.122/0.' and commands to execute 'regsvr32 -silent .\hast.ser' and 'regsvr32 -silent calc'. This indicates the macro is designed to download and execute a second-stage payload.

Heuristics 5

  • Excel 4.0 macro sheet (2 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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • VBA project inside OOXML medium OOXML_VBA
    Document contains vbaProject.bin — VBA macros present
  • External relationship medium OOXML_EXTERNAL_REL
    External target in xl/externalLinks/_rels/externalLink1.bin.rels: IC-Office-Work-Schedule-Template16
  • 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://www.iec.ch
    • http://ns.adobe.com/xap/1.0/
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/photoshop/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceEvent#
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#

Extracted artifacts 4

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
f35edebd65f2486e3f48c3f3aa064d03ff096f2bf9302d6865a1bbca8e954c8b		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 3324 bytes
vbaProject_00.bin
e2b623b050c8dd3b617fa7a3cf0672cd40b5d6248ac15af0e3d3c7928cd515e1		 vba-project OOXML VBA project: xl/vbaProject.bin 20480 bytes
xlm_sheet_00.bin
ab6115cf0c85d0fbbc57b16373ec3177c2fd932c9dd4bbe00a97987876d7db4a		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin 1213 bytes
xlm_sheet_01.bin
2054a4fe6328ca7eb2f39f156ed46ee14c6a1e5be94c807f0daa539bed9d9837		 xlm-macrosheet OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin 756 bytes

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