Office (OOXML) / .XLSM malware analysis — malicious · ced40d5b4e751ac4

MALICIOUS

Office (OOXML) / .XLSM

183.4 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300

MD5: 904379dc152639dee8df059fe44c9402 SHA-1: 2b2c88e65112bf5e1dcc3cab1f2a93f7306cd83a SHA-256: ced40d5b4e751ac482d204e387d70dda916657ebe753c4e4c3c589d162b71f9e

310 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter T1071.001 Application Layer Command and Scripting T1566.001 Phishing T1071.002 Application Layer Targeting

The file exhibits several strong indicators of malicious activity. The presence of Excel 4.0 XLM macro sheets, combined with the use of dangerous formula APIs like `=CALL`, `=EXEC`, `=REGISTER`, and `=FORMULA` to directly invoke WinAPI functions (URLDownloadToFileA, ShellExecuteA, CreateDirectoryA) strongly suggests a downloader attempting to bypass traditional VBA-based detection. The hidden sheets and the embedded URLs further support this assessment. The file is likely designed to exploit vulnerabilities in older versions of Excel that lack robust XLM protection.

Heuristics 7

Excel 4.0 macro sheet (10 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: FORMULA, GOTO, REGISTER, 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.
Binary XLM macro sheet with WinAPI/download strings critical OOXML_XLM_BINARY_WINAPI_STRINGS

Excel 4.0 macro sheet is stored as BIFF12/XLSB binary data and contains Win32 download or process-execution API strings such as URLDownloadToFileA, ShellExecuteA, or CreateDirectoryA. These strings are high-signal in XLM macro sheets and catch payload-download macros that XML-formula scanners cannot parse.
ClamAV: Xls.Downloader.GreenEnable06210-9869360-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.GreenEnable06210-9869360-0
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 10 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 — context-specific rules above attribute URLs they actually evaluated; this rule lists URLs that were present in the bytes but were not otherwise tied to a specific finding.
URL http://schemas.openxmlformats.org/spreadsheetml/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
- http://schemas.microsoft.com/office/spreadsheetml/2014/revision
- http://schemas.microsoft.com/office/spreadsheetml/2015/revision2
- http://schemas.microsoft.com/office/spreadsheetml/2016/revision3
- http://schemas.microsoft.com/office/excel/2006/main
- http://schemas.microsoft.com/office/spreadsheetml/2016/revision6

Extracted artifacts 10

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `1e56e1f2eede302543e5df8b9ebfaea744b26d28977f1390ea971f4b360a26ef`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	3222 bytes
`xlm_sheet_01.xml` `9f05fa9be829be1eefeb660a152567edb54f7c357d0db2659790a946134ef9bd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.xml	1785 bytes
`xlm_sheet_02.xml` `405845b1631a0aa71b486f4418949d96bde2110bb9f06addaf0fcd75e88528c3`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.xml	2657 bytes
`xlm_sheet_03.xml` `43e6f6f4ebc87c4132b97fece91322592028938542550327d7113eb1c83010e5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet4.xml	1849 bytes
`xlm_sheet_04.xml` `49dcda5b792610c41de404d2b70cfc974135ab65a439e8c738a1c9da0fcb9f77`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet5.xml	1771 bytes
`xlm_sheet_05.xml` `d36f154dba963b8e1b114a8eb7856a7559b20af161115ec9858bc4527e63792f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet6.xml	1559 bytes
`xlm_sheet_06.xml` `84c260af46eecb368a56b6975dc52f2fe5cc18e2695b57472a4ec15bdec2c065`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet7.xml	1586 bytes
`xlm_sheet_07.xml` `ad7ce2861628a67d038db82c6e0c4f96565fd87f489a044f5b06b21d72a592e1`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet8.xml	1589 bytes
`xlm_sheet_08.xml` `b58afdef5f0f3f74593fd083f85481e37c174bf42505739468eec6cc33659cb4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet9.xml	1582 bytes
`xlm_sheet_09.xml` `78202619198b2160503b5dd1d62f26d794ff5905704afedefc7df1582494d5b5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1630 bytes

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