Office (OLE) / .XLSX malware analysis — malicious · a3a1edd21f26e824

MALICIOUS

Office (OLE) / .XLSX

323.5 KB Created: 2006-09-16 00:00:00 Authoring application: Microsoft Excel

MD5: 0d62097ec920b832b99821dcdf34ff65 SHA-1: 0c2f4ef792899764c0e6dbb38aae4d6de89217a2 SHA-256: a3a1edd21f26e824532fb4269e238bcaebc018af8c489b787d657d8730210cc8

340 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1105 Ingress Tool Transfer

The sample contains both Excel 4.0 (XLM) macros and VBA code. The XLM macros utilize a CALL function to construct a string that appears to be a path for a downloaded file, and then execute it. The VBA code explicitly uses the URLDownloadToFile API to download a file from the reconstructed URL 'http://e-205.org/ds/1312.gif' to the path 'C:\ervio\'. This indicates a downloader functionality, aiming to fetch and execute a second-stage payload.

Heuristics 7

Reference to URLDownloadToFile API critical SC_STR_URLDOWNLOAD

Reference to URLDownloadToFile API
Excel 4.0 Auto_Open defined name critical OLE_XLM_AUTOOPEN_DEFINEDNAME

oletools recovered an Auto_Open / Auto_Close entry from an Excel 4.0 macro sheet. The raw BIFF name can be tokenized or partially opaque to byte-string checks, but the recovered macro listing confirms the workbook has an XLM auto-execution entry.
XLM Auto_Open with dangerous formula APIs critical OLE_XLM_DANGEROUS_FN

Excel 4.0 macro sheet contains an Auto_Open / Auto_Close entry and dangerous XLM formula APIs that can invoke programs, write files, or transfer control without VBA.
URLDownloadToFile in VBA critical OLE_VBA_DOWNLOAD

URLDownloadToFile in VBA
ClamAV: Doc.Downloader.Docusign0521-9864805-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Doc.Downloader.Docusign0521-9864805-0
Excel 4.0 (XLM) macro sheet present medium OLE_XLM_AUTOOPEN

Workbook contains an Excel 4.0 macro sheet sub-stream — XLM is rarely seen in modern legitimate workbooks and was a major Office malware vector during 2020-2022.
VBA macros detected medium OLE_VBA_MACROS

Document contains VBA macro code

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `4add559fbc909e37ff53ba8479deae9a295d86eb0ed4d06ce7a640c234f275e2`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	1701 bytes
`macros.bas` `256b335e5823b99f7a36dd4cf9683c1bcb2caee7ef57244973558dc0141aa6d4`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	1861 bytes

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