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Java and Command Line Injections in Windows (http://codewhitesec.blogspot.com/2016/02/java-and-command-line-injections-in.html)
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import java.io.IOException; | |
import java.io.InputStream; | |
import java.util.Arrays; | |
public class CommandLine { | |
public static void main(String[] args) throws IOException { | |
args = new String[] { | |
"C:\\Temp\\PrintArguments.exe", | |
"arg 1", | |
"arg 2", | |
"arg 3" | |
}; | |
start(args); | |
} | |
public static void start(String[] args) throws IOException { | |
InputStream in = new ProcessBuilder(Arrays.asList(args)).start().getInputStream(); | |
byte[] buffer = new byte[1024]; | |
int len; | |
while ((len = in.read(buffer)) != -1) { | |
System.out.write(buffer, 0, len); | |
} | |
} | |
} |
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Arguments in Java: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '"""""' | |
CreateProcess command line: | |
"C:\Temp\PrintArguments.exe" """"" | |
argv arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '""' | |
CommandLineToArgvW arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '"' | |
Arguments in Java: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '" "" "' | |
CreateProcess command line: | |
"C:\Temp\PrintArguments.exe" " "" " | |
argv arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: ' " ' | |
CommandLineToArgvW arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: ' "' | |
2: '' | |
Arguments in Java: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '"" ' | |
CreateProcess command line: | |
C:\Temp\PrintArguments.exe """ " | |
argv arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '" ' | |
CommandLineToArgvW arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '"' | |
2: '' | |
Arguments in Java: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '""" ' | |
CreateProcess command line: | |
C:\Temp\PrintArguments.exe """" " | |
argv arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '"' | |
2: '' | |
CommandLineToArgvW arguments: | |
0: 'C:\Temp\PrintArguments.exe' | |
1: '" ' |
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#include <Windows.h> | |
int main(int argc, char *argv[], char **envp) | |
{ | |
int nArgs; | |
LPWSTR * szArgs; | |
printf("argv arguments:\n"); | |
for (int i = 0; i < argc; ++i) printf("%u: '%s'\n", i, argv[i]); | |
printf("CommandLineToArgvW arguments:\n"); | |
szArgs = CommandLineToArgvW(GetCommandLineW(), &nArgs); | |
if (szArgs == NULL) return -1; | |
for (int i = 0; i < nArgs; ++i) wprintf(L"%u: '%ws'\n", i, szArgs[i]); | |
LocalFree(szArgs); | |
return 0; | |
} |
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private ProcessImpl(String cmd[], | |
final String envblock, | |
final String path, | |
final long[] stdHandles, | |
final boolean redirectErrorStream) | |
throws IOException | |
{ | |
String cmdstr; | |
SecurityManager security = System.getSecurityManager(); | |
boolean allowAmbiguousCommands = false; | |
if (security == null) { | |
allowAmbiguousCommands = true; | |
String value = System.getProperty("jdk.lang.Process.allowAmbiguousCommands"); | |
if (value != null) | |
allowAmbiguousCommands = !"false".equalsIgnoreCase(value); | |
} | |
if (allowAmbiguousCommands) { | |
/* 331-344 skipped; legacy mode */ | |
} else { | |
/* 346-383 skipped; strict mode */ | |
} | |
handle = create(cmdstr, envblock, path, | |
stdHandles, redirectErrorStream); | |
/* 389-418 skipped */ | |
} |
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private static String createCommandLine(int verificationType, | |
final String executablePath, | |
final String cmd[]) | |
{ | |
StringBuilder cmdbuf = new StringBuilder(80); | |
cmdbuf.append(executablePath); | |
for (int i = 1; i < cmd.length; ++i) { | |
cmdbuf.append(' '); | |
String s = cmd[i]; | |
if (needsEscaping(verificationType, s)) { | |
cmdbuf.append('"').append(s); | |
// The code protects the [java.exe] and console command line | |
// parser, that interprets the [\"] combination as an escape | |
// sequence for the ["] char. | |
// http://msdn.microsoft.com/en-us/library/17w5ykft.aspx | |
// | |
// If the argument is an FS path, doubling of the tail [\] | |
// char is not a problem for non-console applications. | |
// | |
// The [\"] sequence is not an escape sequence for the [cmd.exe] | |
// command line parser. The case of the [""] tail escape | |
// sequence could not be realized due to the argument validation | |
// procedure. | |
if ((verificationType != VERIFICATION_CMD_BAT) && s.endsWith("\\")) { | |
cmdbuf.append('\\'); | |
} | |
cmdbuf.append('"'); | |
} else { | |
cmdbuf.append(s); | |
} | |
} | |
return cmdbuf.toString(); | |
} |
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private static boolean isQuoted(boolean noQuotesInside, String arg, | |
String errorMessage) { | |
int lastPos = arg.length() - 1; | |
if (lastPos >=1 && arg.charAt(0) == '"' && arg.charAt(lastPos) == '"') { | |
// The argument has already been quoted. | |
if (noQuotesInside) { | |
if (arg.indexOf('"', 1) != lastPos) { | |
// There is ["] inside. | |
throw new IllegalArgumentException(errorMessage); | |
} | |
} | |
return true; | |
} | |
if (noQuotesInside) { | |
if (arg.indexOf('"') >= 0) { | |
// There is ["] inside. | |
throw new IllegalArgumentException(errorMessage); | |
} | |
} | |
return false; | |
} |
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private boolean isShellFile(String executablePath) { | |
String upPath = executablePath.toUpperCase(); | |
return (upPath.endsWith(".CMD") || upPath.endsWith(".BAT")); | |
} |
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// Legacy mode. | |
// Normalize path if possible. | |
String executablePath = new File(cmd[0]).getPath(); | |
// No worry about internal, unpaired ["], and redirection/piping. | |
if (needsEscaping(VERIFICATION_LEGACY, executablePath) ) | |
executablePath = quoteString(executablePath); | |
cmdstr = createCommandLine( | |
//legacy mode doesn't worry about extended verification | |
VERIFICATION_LEGACY, | |
executablePath, | |
cmd); |
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private static boolean needsEscaping(int verificationType, String arg) { | |
// Switch off MS heuristic for internal ["]. | |
// Please, use the explicit [cmd.exe] call | |
// if you need the internal ["]. | |
// Example: "cmd.exe", "/C", "Extended_MS_Syntax" | |
// For [.exe] or [.com] file the unpaired/internal ["] | |
// in the argument is not a problem. | |
boolean argIsQuoted = isQuoted( | |
(verificationType == VERIFICATION_CMD_BAT), | |
arg, "Argument has embedded quote, use the explicit CMD.EXE call."); | |
if (!argIsQuoted) { | |
char testEscape[] = ESCAPE_VERIFICATION[verificationType]; | |
for (int i = 0; i < testEscape.length; ++i) { | |
if (arg.indexOf(testEscape[i]) >= 0) { | |
return true; | |
} | |
} | |
} | |
return false; | |
} |
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String executablePath; | |
try { | |
executablePath = getExecutablePath(cmd[0]); | |
} catch (IllegalArgumentException e) { | |
// Workaround for the calls like | |
// Runtime.getRuntime().exec("\"C:\\Program Files\\foo\" bar") | |
// No chance to avoid CMD/BAT injection, except to do the work | |
// right from the beginning. Otherwise we have too many corner | |
// cases from | |
// Runtime.getRuntime().exec(String[] cmd [, ...]) | |
// calls with internal ["] and escape sequences. | |
// Restore original command line. | |
StringBuilder join = new StringBuilder(); | |
// terminal space in command line is ok | |
for (String s : cmd) | |
join.append(s).append(' '); | |
// Parse the command line again. | |
cmd = getTokensFromCommand(join.toString()); | |
executablePath = getExecutablePath(cmd[0]); | |
// Check new executable name once more | |
if (security != null) | |
security.checkExec(executablePath); | |
} | |
// Quotation protects from interpretation of the [path] argument as | |
// start of longer path with spaces. Quotation has no influence to | |
// [.exe] extension heuristic. | |
cmdstr = createCommandLine( | |
// We need the extended verification procedure for CMD files. | |
isShellFile(executablePath) | |
? VERIFICATION_CMD_BAT | |
: VERIFICATION_WIN32, | |
quoteString(executablePath), | |
cmd); |
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