Office (OOXML) / .XLSM malware analysis — malicious · adfa4a24b8c6031d

MALICIOUS

Office (OOXML) / .XLSM

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

MD5: b9c1d5972caff27cba247ff57f1d1e93 SHA-1: 8e73eaf550bd1e56785c50daf35ab35507c409dc SHA-256: adfa4a24b8c6031df2fc62401b1e5003266f3626119b79b20c0c5dd923fc71ea

250 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1204.002 Malicious File T1059.001 PowerShell T1105 Ingress Tool Transfer

The file is an XLSM document containing Excel 4.0 macros, as indicated by multiple critical heuristic firings including OOXML_XLM_MACROSHEET and OOXML_XLM_DANGEROUS_FN. The macros utilize the FORMULA API to download a DLL payload from several URLs, including "http://daferton.top/30fdh3fdh/update.dll". This indicates a downloader attack pattern. The presence of hidden sheets further supports the malicious intent.

Heuristics 6

Excel 4.0 macro sheet (8 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 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.
ClamAV: Xls.Downloader.GreenOffice01223-9937701-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Xls.Downloader.GreenOffice01223-9937701-0
Hidden worksheet (hidden) 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 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
- 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/spreadsheetml/2016/revision6

Extracted artifacts 8

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `951917452f51508fa7fcbfcbbc9f76ec839f945e614866e11f7a5f7783a1fffb`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.xml	3864 bytes
`xlm_sheet_01.xml` `4077d5ba2f84cdff70678eb9149ba6dbb20869e45eb8e63b9b0fcdc47043ec5a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1279 bytes
`xlm_sheet_02.xml` `347a45d58c3014652d1292cbf3343d054f1a993f8bbed8c27adb3b44f564bd5f`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.xml	1276 bytes
`xlm_sheet_03.xml` `a915ab0143c727ee0ef5570eb5bdaf594955dc963eeb8bec01eda574357378b8`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.xml	1276 bytes
`xlm_sheet_04.xml` `29536788abbc20742436b4dbe8445bce7ba727ab4c76176c3ac8a4664845e7e4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet4.xml	1279 bytes
`xlm_sheet_05.xml` `3af8fd376a06d20ca4f9c51df77d57b89a3903d9a77bd2a99eae044bb2c2656c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet5.xml	1279 bytes
`xlm_sheet_06.xml` `f3986bbddae4964981dc6dbfc11e3e44be66e4a0d3ab73d967e6c786ed5965f2`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet6.xml	1276 bytes
`xlm_sheet_07.xml` `1624f3e7ae6e74a27e3236325272c61f07a98f67f9e5836bf381e0b59e9b1789`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet7.xml	1279 bytes

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