Office (OOXML) / .XLSM malware analysis — malicious · a463f9a8842a5c94

MALICIOUS

Office (OOXML) / .XLSM

41.1 KB Created: 2020-12-07 14:38:21 UTC Authoring application: Microsoft Excel 16.0300

MD5: 9b7c2b0abf5478ef9a23d9a9e87c7835 SHA-1: 6931c4b845a8a952699d9cf85b316e3b3d826a41 SHA-256: a463f9a8842a5c947abaa2bff1b621835ff35f65f9d3272bf1fa5197df9f07d0

210 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, indicated by the 'OOXML_XLM_MACROSHEET' and 'OOXML_XLM_DANGEROUS_FN' heuristics. The 'RETURN()' function is a critical indicator of macro execution that can lead to arbitrary code execution. The VBA code, specifically the 'pagesREviewsd' function, appears to be designed to trigger this macro execution, potentially to download and run a second-stage payload. The presence of a hidden sheet further suggests an attempt to conceal malicious activity.

Heuristics 6

VBA ActiveX event runs worksheet-decoded XLM formulas critical OLE_VBA_ACTIVEX_XLM_CELL_STAGER

VBA code attached to an ActiveX/UserForm event reconstructs formula text from worksheet constants using Split/Replace/Mid or character shifting, then executes it through ExecuteExcel4Macro or Run. This is a high-confidence malware stager that hides XLM formula execution in sheet cells; it is not a document-parser CVE.
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.
Dangerous XLM formula APIs: RETURN 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.
VBA project inside OOXML medium OOXML_VBA

Document contains vbaProject.bin — VBA macros present
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://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 4

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas` `4a71708e274041e7f4b61d5df83028298bc9e092e428acb01e64e07f1b484a5f`	vba-macro	oletools.olevba.extract_macros (decoded VBA source from OOXML)	1832 bytes
`vbaProject_00.bin` `00ae829b8ec632a63471fc108c808cd303a7c070eb0a6af6c8d138c34f5ae10f`	vba-project	OOXML VBA project: xl/vbaProject.bin	18432 bytes
`emf_00.emf` `da935e8d60e93e41bcd7c3fbb1750ef3ac471c3af78afc8945dfbf31eb54a1e1`	ooxml-emf	OOXML EMF part: xl/media/image1.emf	1408 bytes
`xlm_sheet_00.xml` `2b22e750932dab4395a034bb21fc6fc762875f05072e9861cec551e66d6f3c07`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	1026 bytes

Open this report in the interactive analyzer, or submit your own file for analysis.