Malicious Office (OLE) / .XLS — malware analysis report

Static analysis result for SHA-256 45bf4d782eec15ce…

MALICIOUS

Office (OLE) / .XLS

46.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-08
MD5: 2e81d91bc590b987d4e5c5f688c61401 SHA-1: 77238e6371566024f3dd73c639b1b8c20c8ffc11 SHA-256: 45bf4d782eec15ce22609f4ff3cfc73eef77095fa856ebf141ab59957afd9032
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Service Execution: Visual Basic T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: Malicious Applet

The critical heuristics indicate the presence of Excel 4.0 macros with an Auto_Open function that utilizes dangerous APIs, specifically the RUN function. This strongly suggests the macro is designed to execute arbitrary code. The extracted URLs are likely used to download and execute a second-stage payload. The macro sheet contains multiple references to these URLs, indicating a downloader or droppper functionality.

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.

FilenameKindSourceSize
xlm_macros.txt
f02d63843d495ffd8e99f1b7fe5f87a80501a758c9a61d8585f8be9700f36cb3
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7798 bytes