Office (OOXML) / .XLSX malware analysis — malicious · c098e6917b058361

MALICIOUS

Office (OOXML) / .XLSX

26.1 KB Created: 2020-04-29 13:43:05 UTC Authoring application: Microsoft Excel 16.0300

MD5: 76225817c2c6fa0ef5fb563510a23193 SHA-1: 40f81c9ee20da4007ea925ff49f069ad7552a601 SHA-256: c098e6917b05836186b8d9d450ddddbca62532bb20fa283d35cfd6d4ed7fbe00

128 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Service Execution: Service Execution T1204.002 Malicious File: Malicious File

This XLSX file contains multiple Excel 4.0 macro sheets, which is highly suspicious as this macro language is rarely used in legitimate documents. The presence of dangerous XLM functions like RUN, CALL, and FORMULA indicates an intent to execute arbitrary code. These functions are commonly abused to download and execute second-stage payloads, making this a likely delivery mechanism for further malware.

Heuristics 5

Dangerous XLM formula APIs: RUN, CALL, HALT, 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.
Excel 4.0 macro sheet (8 sheet(s)) high 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.
Suspicious extracted artifact medium EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
Hidden worksheet (hidden) low OOXML_HIDDEN_SHEET

Excel workbook contains 8 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.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

Extracted artifacts 8

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.xml` `d286de097658367aefac32ee6fe426b03b50af356f8b56094aaed39be307edbd`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.xml	61161 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 shell/COM execution token(s).
`xlm_sheet_01.xml` `9640497c0ff507fe08458309595566fa54a1bbb675ff8c1c4e3fef1166d14956`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.xml	4138 bytes
`xlm_sheet_02.xml` `60dae18432528a20404b61a5afbd226fe40398fb07b200f305ebfdbc378ee4da`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.xml	1086 bytes
`xlm_sheet_03.xml` `e328b4b853f296edc165979c8601ca7eb153fdb166e3721efbf428e260bf14c6`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet4.xml	1086 bytes
`xlm_sheet_04.xml` `78528101de9b2e78cd9092fc8201aeb512ad77ae0f50fc462186901635e69527`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet5.xml	1086 bytes
`xlm_sheet_05.xml` `521940ec7df2bbbfebc68e759d4b3cf3c0bfda4af39706e05e954eb5ef8cd4b5`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet6.xml	1086 bytes
`xlm_sheet_06.xml` `6a8bfb77cef451b893130c9d059fa0a28cd652f611ac364da308a37a298dda3e`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet7.xml	1086 bytes
`xlm_sheet_07.xml` `d2fedf9d27c4a517d1e3ec1f98966c695db92c569e8c4c3f7f60a30276c08ed4`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet8.xml	1086 bytes

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