Office (OOXML) / .XLSX malware analysis — malicious · 1b6fc736726745e4

MALICIOUS

Office (OOXML) / .XLSX

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

MD5: 0d17b19ea324d2ae08a0473e98498bfc SHA-1: 2f11fa59b4d2c64863881e8084c15c89da09c190 SHA-256: 1b6fc736726745e4d745f373d11ab661bd27db662a6e833b21678c193c06a88c

180 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic

The sample is an XLSX file containing multiple Excel 4.0 macro sheets, as indicated by the OOXML_XLM_MACROSHEET and OOXML_XLSB_INTL_MACROSHEET_IN_XLSX heuristics. The ClamAV detection of 'Multios.Malware.Agent-9976565-0' further confirms its malicious nature. The extracted macro content is heavily obfuscated and truncated, preventing a detailed analysis of its specific actions, but the presence of XLM macros strongly suggests an attempt to execute arbitrary code.

Heuristics 3

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. The macro sheet is stored as XLSB/BIFF12 binary content, which many XML-only OOXML scanners miss.
XLSB international XLM macro sheet hidden in .xlsx critical OOXML_XLSB_INTL_MACROSHEET_IN_XLSX

OOXML package is named .xlsx but contains XLSB workbook parts and an international Excel 4.0 macro sheet. This hides XLM macro execution from scanners that trust the extension or only inspect XML worksheet parts. The technique is macro execution, not a document-parser CVE.
ClamAV: Multios.Malware.Agent-9976565-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Multios.Malware.Agent-9976565-0

Extracted artifacts 8

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `707286be3adee4bb71706f8e33eac4a00ad4798a09b9bc4fcbd508421d42eae3`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	2510 bytes
`xlm_sheet_01.bin` `0b8d1b0cc3345e3192eb316418df0abd4df1724dfc6e89f9b797a3ec3a116666`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	428 bytes
`xlm_sheet_02.bin` `95d18ab8a52ff07f733f6525755497dd373c751fc75f66c9e44a97e72249199e`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.bin	428 bytes
`xlm_sheet_03.bin` `5876bf754443358f21831ded50530fcd64321936ac6276ae052b2274ea7edbdf`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.bin	428 bytes
`xlm_sheet_04.bin` `9ef2819a4f98b9d5f46d61a3b25b15046bac14401ac6aa7b8d5dc8ab2d6a1043`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet4.bin	428 bytes
`xlm_sheet_05.bin` `ac7e512cb4697c7e43c1017c71ac40a12178782019e95f0eacb17164c3a6f458`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet5.bin	428 bytes
`xlm_sheet_06.bin` `04cdb45608f4bf92cacbb735a550851e04e343a904396de0a400f4f175e8b868`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet6.bin	428 bytes
`xlm_sheet_07.bin` `dfb7483e4d4cec3b9ad215a6a4c6f8b61715de3f3ca2d1c76723a9709ece4e4b`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet7.bin	428 bytes

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