Office (OLE) / .XLSX malware analysis — malicious · 3cb2cbbe3b96cce8

MALICIOUS

Office (OLE) / .XLSX

168.5 KB Created: 2008-08-11 04:02:00 Authoring application: Microsoft Excel

MD5: 13b974755ab8ccad61d3e394f2d93a3e SHA-1: f764ce560701f6e53f73b2183541a11bde004985 SHA-256: 3cb2cbbe3b96cce8a122de669c5eecfc447e5df5ddc44823b4539338d325207a

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1059.001 PowerShell T1059.003 Windows Command Shell

The file contains Excel 4.0 (XLM) macro sheets, specifically triggering the Auto_Open function. Heuristics indicate the use of dangerous formula APIs, including the 'RUN' function, which is commonly used to execute arbitrary commands. The presence of an Auto_Open entry strongly suggests the macro will execute automatically upon opening the workbook, likely to download and execute a second-stage payload.

Heuristics 3

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.
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`xlm_macros.txt` `dd496a4438005adec0c4b655244b3f0b15a219843c25647f8f8b140c45d1eb64`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	80227 bytes

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