Xls.Dropper.Agent — Office (OLE) malware analysis

Static analysis result for SHA-256 753352c2a516d22a…

MALICIOUS

Office (OLE)

195.0 KB Created: 2020-07-16 08:15:40 Authoring application: Microsoft Excel First seen: 2020-09-15
MD5: b56d7cef5df637821f7ab1e451ad9cd2 SHA-1: d81c3a2cd65d1c3487f1fcb342002856a90e7567 SHA-256: 753352c2a516d22a8192a723b4181f91a83d24b20bfbed4888eb819b8c9ea7c8
280 Risk Score

Malware Insights

Xls.Dropper.Agent · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic T1566.001 Spearphishing Attachment

The sample is identified as malicious by ClamAV with the signature Xls.Dropper.Agent-9157134-0. Static analysis revealed Excel 4.0 macros with an Auto_Open function, which is designed to execute automatically. The macro sheet also contains environment evasion techniques and dangerous API calls, indicating an attempt to download and execute a secondary payload. The presence of an 'enable lure' heuristic further suggests user interaction is expected to trigger the malicious execution.

Heuristics 6

  • ClamAV: Xls.Dropper.Agent-9157134-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Xls.Dropper.Agent-9157134-0
  • 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.
  • XLM Auto_Open environment-evasion close gate critical OLE_XLM_ENVIRONMENT_EVASION_CLOSE
    Excel 4.0 macro sheet auto-executes environment checks with GET.WORKSPACE / GET.WINDOW, then shows a fake corruption/error message and closes the workbook when the host fails those checks. This is a malware sandbox-evasion pattern, even when the later payload stage is hidden behind obfuscated defined-name flow.
  • 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.
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
xlm_macros.txt xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 75771 bytes
SHA-256: 28774d2206099a34269b28b9dc05b2fbbb1ca3d3f1c270d0babde4840d714f81
Preview script
First 1,000 lines of the extracted script
' 0085     10 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  o
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     24 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  NQkNRfpLYLxZutW
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet1
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet1
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet1
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet1
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet1
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0018     31 LABEL : Cell Value, String Constant - ajHCfhOUnvlRMMLQ len=0 
' 0018     53 LABEL : Cell Value, String Constant - aKUaWizBWXgElPeLRksiOJKINxqxcDoFILDcFj len=0 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  o!DU53916 
' 0018     41 LABEL : Cell Value, String Constant - bhBJxdZZYcOUcsTSiYbTrVzxfU len=0 
' 0018     59 LABEL : Cell Value, String Constant - bIlBhoHPFkfgejVOVyaLbfiZybHqmbvlcqBjjWJjGThP len=0 
' 0018     38 LABEL : Cell Value, String Constant - BIPfGGVLOGeImkSHbSJWgQP len=0 
' 0018     46 LABEL : Cell Value, String Constant - BKFixRkEynTcdbgRLSvJIYcfWvLDnVX len=0 
' 0018     23 LABEL : Cell Value, String Constant - BsRgZJrt len=0 
' 0018     58 LABEL : Cell Value, String Constant - BuNKhDbTQbsHcQZxrVXEYdlbHQQPUqxFjwvMPSKixqa len=0 
' 0018     37 LABEL : Cell Value, String Constant - BuNKhDbUQbsHcQaxsWXEYd len=0 
' 0018     46 LABEL : Cell Value, String Constant - bVnXtdntpCThpqzXSvxekEMChcdbgRY len=0 
' 0018     21 LABEL : Cell Value, String Constant - CbCNHZ len=0 
' 0018     20 LABEL : Cell Value, String Constant - CDNWR len=0 
' 0018     24 LABEL : Cell Value, String Constant - CdxcBSsTe len=0 
' 0018     18 LABEL : Cell Value, String Constant - CFZ len=0 
' 0018     37 LABEL : Cell Value, String Constant - CGUQzNmmOWiLeKhzZzLFXH len=0 
' 0018     21 LABEL : Cell Value, String Constant - COefBD len=0 
' 0018     55 LABEL : Cell Value, String Constant - CriwHppcdENZCVzYqCqnhzwUEOUQcstPRaxfIYFL len=0 
' 0018     61 LABEL : Cell Value, String Constant - CRmnxHCfuOhBvkQZaYdOIPsGFVZbTsIzkSUpSWkuPdQDdz len=0 
' 0018     22 LABEL : Cell Value, String Constant - CrXSSRW len=0 
' 0018     20 LABEL : Cell Value, String Constant - DBGqj len=0 
' 0018     64 LABEL : Cell Value, String Constant - dbJxSIyNXGGssUcpRlQoGSHExQNjTekgrJKfhqOuYoVbuDrXT len=0 
' 0018     37 LABEL : Cell Value, String Constant - DDemybuaxQcQOIaXtdotpC len=0 
' 0018     62 LABEL : Cell Value, String Constant - DENXSvLdxRLBgpqoteXeJWVlorjJXQBikFhmzLfsgStQPqY len=0 
' 0018     38 LABEL : Cell Value, String Constant - DexdCTfTRLdawgrxtFWXstE len=0 
' 0018     49 LABEL : Cell Value, String Constant - DNkfJKqLQYOtDECHekrWjiyCFwWkdOvxSu len=0 
' 0018     30 LABEL : Cell Value, String Constant - dNYdalDRZajICfh len=0 
' 0018     59 LABEL : Cell Value, String Constant - DPfgCENkSvLrxRZPuppoteXeJjVlorjIlQzvkFvmzKts len=0 
' 0018     41 LABEL : Cell Value, String Constant - DpQmyNuMyDcQOIaXtQouqCFUpq len=0 
' 0018     22 LABEL : Cell Value, String Constant - dWdIiUk len=0 
' 0018     23 LABEL : Cell Value, String Constant - DyKbqxzJ len=0 
' 0018     22 LABEL : Cell Value, String Constant - DymHxoD len=0 
' 0018     24 LABEL : Cell Value, String Constant - dyzKTOr
... (truncated)