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

Static analysis result for SHA-256 3538339d5f03c7d8…

MALICIOUS

Office (OLE) / .XLS

214.5 KB Created: 2020-05-03 13:28:15 Authoring application: Microsoft Excel
MD5: cb92488ced366a61813a1e028f284310 SHA-1: e4d9d904547622febecee14458066c913a5cf9b5 SHA-256: 3538339d5f03c7d80e4438fbae6ced00941ccb33329053ad263b0131497dc8c3
360 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 File T1059.003 Command and Scripting Interpreter: Windows Command Shell

The file contains critical Excel 4.0 (XLM) macros with an Auto_Open entry, indicating it's designed to execute code upon opening. Heuristics also indicate the use of ShellExecute and certutil, suggesting the macro is likely used to download and execute a second-stage payload. The VBA macros present do not appear to contain malicious functionality themselves but are likely present for obfuscation or as a fallback.

Heuristics 9

  • 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.
  • ClamAV: Ole2.Macro.Agent-9858864-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Ole2.Macro.Agent-9858864-1
  • Heap-spray pattern detected high SC_HEAP_SPRAY
    Repeated 0x41 (A) bytes found
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Reference to certutil (download/decode) high SC_STR_CERTUTIL
    Reference to certutil (download/decode)
  • NOP-equivalent sled detected medium SC_NOP_EQUIV_SLED
    Long run of 0x61 bytes
  • 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.

FilenameKindSourceSize
xlm_macros.txt
0536ca05c626c663fff2d889482b31670fa4e1b39585d04fdb2b364cd87ef239		 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 5271 bytes
macros.bas
d780f47720fad4be3a3582d269b84614717794a4727acfd59e22f5aa4f57778a		 vba-macro oletools.olevba.extract_macros (decoded VBA source) 1710 bytes

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