Office (OOXML) / .XLSX malware analysis — malicious · 7c3736d3a14fe877

MALICIOUS

Office (OOXML) / .XLSX

371.6 KB Created: 2021-08-16 09:36:27 UTC Authoring application: Microsoft Excel 12.0000

MD5: ae44481e40a79ab9e42345967853a91f SHA-1: 75ba1eae505a453424464f8483d40b4f4935f61c SHA-256: 7c3736d3a14fe8777d1fee62ddfdd65ace4b726c4bd0f93e885d6d8b623f1110

60 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel spreadsheet containing Excel 4.0 macros, indicated by the OOXML_XLM_MACROSHEET heuristic. These macros are often used to download and execute malicious payloads. While the specific commands within the macro are truncated and obfuscated, the presence of XLM macros strongly suggests an attempt to execute arbitrary code, likely for further infection.

Heuristics 1

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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `cc0713d0f065c09034d1805e9fd12bfcc533df02f6455372e968cefee18eb3dc`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	614849 bytes

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