Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 c83c1b46cbb71b30…

MALICIOUS

Office (OLE)

197.5 KB Created: 2020-07-05 19:30:39 Authoring application: Microsoft Excel First seen: 2020-07-24
MD5: d82a33041941c0e5ec5e9b75f49f35cf SHA-1: 4004f1050d5f525d289d2fbccf27f3ef118ea82f SHA-256: c83c1b46cbb71b300188adc0f9890bc2fb9a82a8a2564d8e7f7bbb1635beb1e4
220 Risk Score

Malware Insights

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

The sample is an Excel file containing Excel 4.0 macros, indicated by multiple critical heuristics including OLE_XLM_AUTOOPEN and OLE_XLM_DANGEROUS_FN. The presence of an Auto_Open entry suggests the macro will execute automatically upon opening the document. The heuristics also indicate environment evasion techniques and a lure to enable macros, pointing towards a malicious dropper. The specific dangerous API used in the macro is 'RUN', which is typically used to execute external commands or download payloads.

Heuristics 5

  • 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) 74820 bytes
SHA-256: 740db7bcbc3b12072a1f05bb2491820fa3d0d2f097cf3061aa8b92af8be19f28
Preview script
First 1,000 lines of the extracted script
' 0085     10 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  x
' 0085     21 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  lDosTHFyROkG
' 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     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     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     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet2
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet3
' 0085     15 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, hidden -  Sheet3
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0018     23 LABEL : Cell Value, String Constant - aaZePIPt len=0 
' 0018     21 LABEL : Cell Value, String Constant - alrnyQ len=0 
' 0018     53 LABEL : Cell Value, String Constant - anCjBmqQFCvOLiEcieqtIdfoysWmFZsmcIRRQU len=0 
' 0018     17 LABEL : Cell Value, String Constant - at len=0 
' 0018     23 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open len=7 ptgRef3d  x!IY50964 
' 0018     20 LABEL : Cell Value, String Constant - besOQ len=0 
' 0018     60 LABEL : Cell Value, String Constant - BGqxFVvuLBEvUxcaIwRIyMWFFssTcoRkQnGSGDwPMjTdj len=0 
' 0018     41 LABEL : Cell Value, String Constant - bkljoMSZERQgjmeDSLvdfzchur len=0 
' 0018     23 LABEL : Cell Value, String Constant - bQkbSfqZ len=0 
' 0018     29 LABEL : Cell Value, String Constant - bQkbSfqZYMxZvI len=0 
' 0018     59 LABEL : Cell Value, String Constant - BRxEXfUzvvtykdkPpbquxpOrWGCqLBrGQyylYzViwevh len=0 
' 0018     30 LABEL : Cell Value, String Constant - bTPbrHcQZwrVXEX len=0 
' 0018     57 LABEL : Cell Value, String Constant - BVxCQNvJiiKSeHaGevWvHBTDZJUaWhyNVWgEybdKQj len=0 
' 0018     26 LABEL : Cell Value, String Constant - BwJaoKxHeZD len=0 
' 0018     21 LABEL : Cell Value, String Con
... (truncated)