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

Static analysis result for SHA-256 2877c69b79d6087d…

MALICIOUS

Office (OOXML) / .XLSM

866.2 KB Created: 2018-09-27 10:58:35 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2025-12-25
MD5: a78f018814b6024e31be8f343afcb322 SHA-1: 0e638fc2c18b1fba8bce90157629d5c85c861bce SHA-256: 2877c69b79d6087d714c6e31f0365e935400c25968aa085e3a55a8ed6d766987
250 Risk Score

Malware Insights

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

The file is an XLSM document containing obfuscated VBA macros, specifically a Workbook_Open auto-execution loader. The presence of CreateObject and execution sink calls, along with external relationships, indicates an attempt to download and execute a secondary payload. The obfuscated nature of the VBA code suggests malicious intent, likely to evade detection.

Heuristics 8

  • Obfuscated auto-exec VBA loader critical OLE_VBA_OBFUSCATED_AUTOEXEC_LOADER
    Auto-exec VBA reconstructs strings with a heavy custom decoder (numeric char-array, repeated hex-string decode, or junk-token Replace removal) and feeds them to a COM-instantiation or execution sink. This obfuscated-loader shape keeps CreateObject/Shell/URL indicators out of the macro source.
  • Workbook_Open macro high OLE_VBA_WBOPEN
    Workbook_Open macro
  • CreateObject call high OLE_VBA_CREATEOBJ
    CreateObject call
  • External relationship high OOXML_EXTERNAL_REL
    External target in xl/externalLinks/_rels/externalLink4.xml.rels: file:///C:\Users\sruthi.gundeti\Desktop\UAT\GSTR_9C_Offline_Utility_84\GSTR_9C_Offline_Utility\GSTR_9C_Offline_Utility_2
  • VBA p-code auto-exec with execution tokens high OLE_VBA_PCODE_AUTOEXEC_EXEC
    Compiled VBA/cache stream contains an auto-execution token together with shell/download/object-execution tokens. This catches p-code-only or source-extraction-failure macro documents where visible source is unavailable.
  • VBA project inside OOXML medium OOXML_VBA
    Document contains a VBA project — VBA macros present
  • Hidden worksheet (hidden, veryHidden) low OOXML_HIDDEN_SHEET
    Excel workbook contains 11 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 https://github.com/VBA-tools/VBA-JSON
    • http://www.vbaccelerator.com/home/VB/Code/Techniques/RunTime_Debug_Tracing/VB6_Tracer_Utility_zip_cStringBuilder_cls.asp
    • https://github.com/VBA-tools/VBA-JSON/pull/82
    • https://github.com/VBA-tools/VBA-UtcConverter
    • http://www.frez.co.uk
    • http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/xap/1.0/sType/ResourceRef#
    • https://infosystechnologies-my.sharepoint.com/Users/sruthi.gundeti/Desktop/UAT/GSTR_9C_Offline_Utility_84/GSTR_9C_Offlin
    • https://infosystechnologies-my.sharepoint.com/Users/sruthi.gundeti/Desktop/UAT/GSTR_9C_Offline_Utility_84/GSTR_9C_Offline_Utility/GSTR_9C_Offline_Utility_2.7/GSTR
    • https://infosystechnologies-my.sharepoint.com/Users/richi.jain/AppData/Local/Temp/Temp1_GSTR_4_Offline_Utility.zip/GSTR_
    • https://infosystechnologies-my.sharepoint.com/Users/richi.jain/AppData/Local/Temp/Temp1_GSTR_4_Offline_Utility.zip/GSTR_4_Offline_Utility_v3.0.xls
    • https://infosystechnologies-my.sharepoint.com/Users/ashutosh.khaitan/Desktop/Worksheet
    • https://infosystechnologies-my.sharepoint.com/Users/pallav_yadav/Documents/GSTR_4_Offline_Utility_v3.0_new_PY.xls
    • http://www.opensource.org/licenses/mit-license.php
    • http://code.google.com/p/vba-json/
    • http://msdn.microsoft.com/en-us/library/windows/desktop/ms724421.aspx
    • http://msdn.microsoft.com/en-us/library/windows/desktop/ms724949.aspx
    • http://msdn.microsoft.com/en-us/library/windows/desktop/ms725485.aspx
    • http://support.microsoft.com/kb/269370
    • http://www.ietf.org/rfc/rfc4627.txt
    • https://support.microsoft.com/en-us/kb/272138
    • http://www.opensource.org/licenses/mit-license.php)�

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
macros.bas
5861ea419c57f0c9cefb41e4991fa1d1a19458b4a234d2010074e2005c778ae5		 vba-macro oletools.olevba.extract_macros (decoded VBA source from OOXML) 589124 bytes
vbaProject_00.bin
bfaa498adf302c1d40387491e929f91b2dbef9ed599298915eebca51f6e67647		 vba-project OOXML VBA project: xl/vbaProject.bin 1524736 bytes

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