Office (OLE) / .XLS malware analysis — malicious · ac910715ef604deb

MALICIOUS

Office (OLE) / .XLS

35.5 KB Created: 2020-11-27 11:43:25 Authoring application: Microsoft Excel First seen: 2022-03-24

MD5: 5bc41200211bb73ca051e74c52a44d33 SHA-1: dea1701116f271b9372eeb11043232bb5b546bdb SHA-256: ac910715ef604deb1118c00532575b3e6b2e0e66dd8e85a7d08b6d7a123e90fd

140 Risk Score

Malware Insights

MITRE ATT&CK

T1059.005 Visual Basic T1566.001 Spearphishing Attachment

This Excel file contains Excel 4.0 (XLM) macros, specifically an Auto_Open macro, which is a known technique for executing malicious code. The critical heuristic firings confirm the presence of a dangerous formula API within the Auto_Open macro, indicating an intent to run arbitrary commands. While the specific payload is not detailed, the presence of an Auto_Open macro strongly suggests a malicious execution flow.

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` `de913fc95d57ceea10e912e3a1e4cf4d936ec3152abc19845144b67d070a8ca3`	xlm-macro	oletools.olevba.extract_all_macros (XLM macro listing)	6561 bytes

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