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

Static analysis result for SHA-256 f40d57aaf9c135ee…

MALICIOUS

Office (OLE) / .XLS

70.5 KB Created: 2015-06-05 18:19:34 Authoring application: Microsoft Excel First seen: 2022-06-07
MD5: a2106053461e1a9b906b8b62675de25f SHA-1: d03b894ab519af1e5d978d0175cb22a0d5fb7f40 SHA-256: f40d57aaf9c135ee4b36dd57d46d2aa26f506661950d9b16a98b857b41c653e5
140 Risk Score

Malware Insights

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

The critical heuristics OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN indicate the presence of Excel 4.0 macros designed to execute automatically upon opening. The macro uses the RUN function, which is a dangerous API, suggesting it's intended to download and execute a second-stage payload from one of the provided URLs. The extracted URLs are the primary indicators of compromise.

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
b15b1a7eda5b33086d8276c3ce6587701b6f26d4c243b84df03390c1913f7d50
xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 7806 bytes