Office (OOXML) / .XLSX malware analysis — malicious · c9813d00b016d7ce

MALICIOUS

Office (OOXML) / .XLSX

117.2 KB Created: 2015-06-05 18:19:34 UTC Authoring application: Microsoft Excel 16.0300 First seen: 2022-03-15

MD5: 9305a93306bcfc0e81d1bcf8a0716a37 SHA-1: 3dfb6b89af41aea8bf39714e92426a638afe0bc9 SHA-256: c9813d00b016d7ce0ad3b1354853e5b2e702f0eeb3acba0f34fd319acdbb352f

180 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic for Applications T1204.002 Malicious File

The file is an XLSX document containing multiple Excel 4.0 macro sheets, identified by the OOXML_XLM_MACROSHEET heuristic. These macros appear to be designed to download a second-stage payload from the reconstructed URL 'http://a.filea.url/R'. The presence of these macros and the download functionality strongly suggest a malicious intent, likely to deliver further malware. The ClamAV detection further corroborates the malicious nature of the file.

Heuristics 3

Excel 4.0 macro sheet (12 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-10042426-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Multios.Malware.Agent-10042426-0

Extracted artifacts 12

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_sheet_00.bin` `e541f768a6a2761f1eb330f36fa4854aa79d685e958fba24945d0f470a5c8620`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet1.bin	871 bytes
`xlm_sheet_01.bin` `0d0844264380b8dadbba0d2074e9c73b38a92bd41acd11a8911bcf11bfae4dd2`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet3.bin	674 bytes
`xlm_sheet_02.bin` `fcbee97f0dd0396d2166b27e70dc5f329138d91e33cacefc90780771d2c89aca`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet1.bin	3588 bytes
`xlm_sheet_03.bin` `9a9c00e5c670d9cb9ebbebc0e8eb74c5dbab1cc8cd9e7ffb4a8841887c938b52`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet2.bin	1269 bytes
`xlm_sheet_04.bin` `b8caa8271c2f12b728bdb0b32921f704c74d345971d996e432db17dc7447a0c1`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet3.bin	737 bytes
`xlm_sheet_05.bin` `5acb5cd8473f658ac1af292f8be69bb3d1e3ad2da2b48975c4cdcaf26c0ce9b9`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet4.bin	674 bytes
`xlm_sheet_06.bin` `9c7f0265f4841d89c0d2dbb41a0e7ff0d6f6e1eee1f2521467877a38b47fdaf2`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet4.bin	672 bytes
`xlm_sheet_07.bin` `266823ec560e31f11854528dcc8a208cadf42a92be72a59d3e08dff40b2cf09a`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet5.bin	562 bytes
`xlm_sheet_08.bin` `59abb19e07a0c85880d3e936983a6afd5475b6de992fac76e4164836c9f8539c`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet8.bin	393 bytes
`xlm_sheet_09.bin` `3568da1cb305e32670f31b9f2e0e2e544620438fc48e5295397de622e00e563d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet6.bin	442 bytes
`xlm_sheet_10.bin` `49977c4c3cbb189580a89e6d184b0137682ae93d0aa4c13b2c8b6bb201cf7535`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/sheet2.bin	754 bytes
`xlm_sheet_11.bin` `a6ac0305669a45ec3d5a9c0fdb6bc74f328641eb09ba1853fc9972b2728de61d`	xlm-macrosheet	OOXML XLM macro sheet: xl/macrosheets/intlsheet7.bin	393 bytes

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