Office (OOXML) / .XLSX malware analysis — malicious · 2790deffa86eb2a0

MALICIOUS

Office (OOXML) / .XLSX

58.7 KB Created: 2021-10-27 10:31:49 UTC Authoring application: Microsoft Excel 12.0000

MD5: 433b1b08c5064e05f7d0427ec878bcc0 SHA-1: 3e3e69d03b4c2692a6f39d504f03c966158fa483 SHA-256: 2790deffa86eb2a0c11c7ac32404036f639eeddda05554df85cfabada5382d21

60 Risk Score

Malware Insights

MITRE ATT&CK

T1204 User Execution

The presence of an Excel 4.0 macro sheet indicates an attempt to exploit legacy scripting capabilities within Microsoft Office applications, specifically targeting users who enable macros. The script reconstructs a path "C:\ProgramData\fnsfunsgrgngkjfsgnd@.@.@.rtf@.@" which suggests it aims to access or download files from this location on the victim's machine. This behavior aligns with common tactics used by malware families leveraging VBA/XLM scripts to achieve persistence or further compromise through user execution. However, without more context about the specific payload or its origin, attributing this sample to a known malware family remains uncertain.

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` `d4e48d39b46cb6a9805db7dcd4e2c6ad00fd3e238a15325e424bd82eb656f240`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	5488 bytes

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