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Jan-Eremicollet
Jan-E
authored and
remicollet
committed
Add proc_open escaping for cmd file execution Backport CVE-2024-1874: Command injection via array-ish $command parameter of proc_open See remicollet/php-src-security#14 
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4 files changed

+169
-5
lines changed

4 files changed

+169
-5
lines changed

‎ext/standard/proc_open.c

Lines changed: 82 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -492,11 +492,33 @@ static void append_backslashes(smart_string *str, size_t num_bs)
492492
}
493493
}
494494

495-
/* See https://docs.microsoft.com/en-us/cpp/cpp/parsing-cpp-command-line-arguments */
496-
static void append_win_escaped_arg(smart_string *str, char *arg)
495+
/* See https://docs.microsoft.com/en-us/cpp/cpp/parsing-cpp-command-line-arguments and
496+
* https://learn.microsoft.com/en-us/archive/blogs/twistylittlepassagesallalike/everyone-quotes-command-line-arguments-the-wrong-way */
497+
const char *special_chars = "()!^\"<>&|%";
498+
499+
static bool is_special_character_present(const char *arg)
500+
{
501+
for (size_t i = 0; i < strlen(arg); ++i) {
502+
if (strchr(special_chars, arg[i]) != NULL) {
503+
return true;
504+
}
505+
}
506+
return false;
507+
}
508+
509+
static void append_win_escaped_arg(smart_string *str, char *arg, bool is_cmd_argument)
497510
{
498511
char c;
499512
size_t num_bs = 0;
513+
bool has_special_character = false;
514+
515+
if (is_cmd_argument) {
516+
has_special_character = is_special_character_present(arg);
517+
if (has_special_character) {
518+
/* Escape double quote with ^ if executed by cmd.exe. */
519+
smart_string_appendc(str, '^');
520+
}
521+
}
500522
smart_string_appendc(str, '"');
501523
while ((c = *arg)) {
502524
if (c == '\\') {
@@ -507,20 +529,73 @@ static void append_win_escaped_arg(smart_string *str, char *arg)
507529
num_bs = num_bs * 2 + 1;
508530
}
509531
append_backslashes(str, num_bs);
532+
if (has_special_character && strchr(special_chars, c) != NULL) {
533+
/* Escape special chars with ^ if executed by cmd.exe. */
534+
smart_string_appendc(str, '^');
535+
}
510536
smart_string_appendc(str, c);
511537
num_bs = 0;
512538
}
513539
arg++;
514540
}
515541
append_backslashes(str, num_bs * 2);
542+
if (has_special_character) {
543+
/* Escape double quote with ^ if executed by cmd.exe. */
544+
smart_string_appendc(str, '^');
545+
}
516546
smart_string_appendc(str, '"');
517547
}
518548

549+
static inline int stricmp_end(const char* suffix, const char* str) {
550+
size_t suffix_len = strlen(suffix);
551+
size_t str_len = strlen(str);
552+
553+
if (suffix_len > str_len) {
554+
return -1; /* Suffix is longer than string, cannot match. */
555+
}
556+
557+
/* Compare the end of the string with the suffix, ignoring case. */
558+
return _stricmp(str + (str_len - suffix_len), suffix);
559+
}
560+
561+
static bool is_executed_by_cmd(const char *prog_name)
562+
{
563+
/* If program name is cmd.exe, then return true. */
564+
if (_stricmp("cmd.exe", prog_name) == 0 || _stricmp("cmd", prog_name) == 0
565+
|| stricmp_end("\\cmd.exe", prog_name) == 0 || stricmp_end("\\cmd", prog_name) == 0) {
566+
return true;
567+
}
568+
569+
/* Find the last occurrence of the directory separator (backslash or forward slash). */
570+
char *last_separator = strrchr(prog_name, '\\');
571+
char *last_separator_fwd = strrchr(prog_name, '/');
572+
if (last_separator_fwd && (!last_separator || last_separator < last_separator_fwd)) {
573+
last_separator = last_separator_fwd;
574+
}
575+
576+
/* Find the last dot in the filename after the last directory separator. */
577+
char *extension = NULL;
578+
if (last_separator != NULL) {
579+
extension = strrchr(last_separator, '.');
580+
} else {
581+
extension = strrchr(prog_name, '.');
582+
}
583+
584+
if (extension == NULL || extension == prog_name) {
585+
/* No file extension found, it is not batch file. */
586+
return false;
587+
}
588+
589+
/* Check if the file extension is ".bat" or ".cmd" which is always executed by cmd.exe. */
590+
return _stricmp(extension, ".bat") == 0 || _stricmp(extension, ".cmd") == 0;
591+
}
592+
519593
static char *create_win_command_from_args(HashTable *args)
520594
{
521595
smart_string str = {0};
522596
zval *arg_zv;
523-
zend_bool is_prog_name = 1;
597+
bool is_prog_name = true;
598+
bool is_cmd_execution = false;
524599
int elem_num = 0;
525600

526601
ZEND_HASH_FOREACH_VAL(args, arg_zv) {
@@ -530,11 +605,13 @@ static char *create_win_command_from_args(HashTable *args)
530605
return NULL;
531606
}
532607

533-
if (!is_prog_name) {
608+
if (is_prog_name) {
609+
is_cmd_execution = is_executed_by_cmd(ZSTR_VAL(arg_str));
610+
} else {
534611
smart_string_appendc(&str, ' ');
535612
}
536613

537-
append_win_escaped_arg(&str, ZSTR_VAL(arg_str));
614+
append_win_escaped_arg(&str, ZSTR_VAL(arg_str), !is_prog_name && is_cmd_execution);
538615

539616
is_prog_name = 0;
540617
zend_string_release(arg_str);

‎ext/standard/tests/general_functions/ghsa-pc52-254m-w9w7_1.phpt

Lines changed: 29 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
--TEST--
2+
GHSA-54hq-v5wp-fqgv - proc_open does not correctly escape args for bat files
3+
--SKIPIF--
4+
<?php
5+
if( substr(PHP_OS, 0, 3) != "WIN" )
6+
die('skip Run only on Windows');
7+
?>
8+
--FILE--
9+
<?php
10+
11+
$batch_file_content = <<<EOT
12+
@echo off
13+
powershell -Command "Write-Output '%1%'"
14+
EOT;
15+
$batch_file_path = __DIR__ . '/ghsa-54hq-v5wp-fqgv.bat';
16+
17+
file_put_contents($batch_file_path, $batch_file_content);
18+
19+
$descriptorspec = [STDIN, STDOUT, STDOUT];
20+
$proc = proc_open([$batch_file_path, "\"&notepad.exe"], $descriptorspec, $pipes);
21+
proc_close($proc);
22+
23+
?>
24+
--EXPECT--
25+
"&notepad.exe
26+
--CLEAN--
27+
<?php
28+
@unlink(__DIR__ . '/ghsa-54hq-v5wp-fqgv.bat');
29+
?>

‎ext/standard/tests/general_functions/ghsa-pc52-254m-w9w7_2.phpt

Lines changed: 29 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
--TEST--
2+
GHSA-54hq-v5wp-fqgv - proc_open does not correctly escape args for cmd files
3+
--SKIPIF--
4+
<?php
5+
if( substr(PHP_OS, 0, 3) != "WIN" )
6+
die('skip Run only on Windows');
7+
?>
8+
--FILE--
9+
<?php
10+
11+
$batch_file_content = <<<EOT
12+
@echo off
13+
powershell -Command "Write-Output '%1%'"
14+
EOT;
15+
$batch_file_path = __DIR__ . '/ghsa-54hq-v5wp-fqgv.cmd';
16+
17+
file_put_contents($batch_file_path, $batch_file_content);
18+
19+
$descriptorspec = [STDIN, STDOUT, STDOUT];
20+
$proc = proc_open([$batch_file_path, "\"&notepad<>^()!.exe"], $descriptorspec, $pipes);
21+
proc_close($proc);
22+
23+
?>
24+
--EXPECT--
25+
"&notepad<>^()!.exe
26+
--CLEAN--
27+
<?php
28+
@unlink(__DIR__ . '/ghsa-54hq-v5wp-fqgv.cmd');
29+
?>

‎ext/standard/tests/general_functions/ghsa-pc52-254m-w9w7_3.phpt

Lines changed: 29 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,29 @@
1+
--TEST--
2+
GHSA-54hq-v5wp-fqgv - proc_open does not correctly escape args for cmd executing batch files
3+
--SKIPIF--
4+
<?php
5+
if( substr(PHP_OS, 0, 3) != "WIN" )
6+
die('skip Run only on Windows');
7+
?>
8+
--FILE--
9+
<?php
10+
11+
$batch_file_content = <<<EOT
12+
@echo off
13+
powershell -Command "Write-Output '%1%'"
14+
EOT;
15+
$batch_file_path = __DIR__ . '/ghsa-54hq-v5wp-fqgv.bat';
16+
17+
file_put_contents($batch_file_path, $batch_file_content);
18+
19+
$descriptorspec = [STDIN, STDOUT, STDOUT];
20+
$proc = proc_open(["cmd.exe", "/c", $batch_file_path, "\"&notepad.exe"], $descriptorspec, $pipes);
21+
proc_close($proc);
22+
23+
?>
24+
--EXPECT--
25+
"&notepad.exe
26+
--CLEAN--
27+
<?php
28+
@unlink(__DIR__ . '/ghsa-54hq-v5wp-fqgv.bat');
29+
?>

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