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GolangDynamicStringRecovery.java
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GolangDynamicStringRecovery.java
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//Finds and creates dynamically allocated strings based on the Golang stringStruct
//@author Max 'Libra' Kersten of Trellix' Advanced Research Center, based on the work by padorka@cujoai (https://github.com/getCUJO/ThreatIntel/blob/master/Scripts/Ghidra/find_dynamic_strings.py)
//@category Golang
//@keybinding
//@menupath
//@toolbar
import java.util.ArrayList;
import java.util.List;
import ghidra.app.script.GhidraScript;
import ghidra.program.model.address.Address;
import ghidra.program.model.lang.OperandType;
import ghidra.program.model.lang.Register;
import ghidra.program.model.listing.Data;
import ghidra.program.model.listing.Instruction;
import ghidra.program.model.mem.MemoryBlock;
import ghidra.program.model.scalar.Scalar;
import ghidra.program.model.util.CodeUnitInsertionException;
import ghidra.util.exception.CancelledException;
public class GolangDynamicStringRecovery extends GhidraScript {
/**
* A boolean which defines if logging should be enabled. When prioritising
* speed, one might not be interested in getting all messages, but rather only
* the concluding message, along with potential error messages. As such, this
* boolean specifies if more logging should be enabled or disabled.</br>
* </br>
* The default value of this field is <code>true</code>.
*/
private static final boolean ENABLE_LOGGING = true;
/**
* The size of a pointer on X86
*/
private static final int POINTER_SIZE_X86 = 4;
/**
* The size of a pointer on X64
*/
private static final int POINTER_SIZE_X64 = 8;
/**
* The number of recovered dynamic strings
*/
private static int stringCount = 0;
@Override
protected void run() throws Exception {
/*
* Get the language ID and the program's pointer size and store those locally,
* as they are re-used multiple times
*/
String languageId = currentProgram.getLanguageID().toString();
int pointerSize = currentProgram.getDefaultPointerSize();
/*
* Based on the language ID, the dynamic strings need to be recovered
* differently
*/
if (languageId.startsWith("ARM")) { // 32-bit ARM
resolve32BitArm();
} else if (languageId.startsWith("AARCH64")) { // 64-bit ARM
resolve64BitArm();
} else if (languageId.startsWith("x86") && pointerSize == POINTER_SIZE_X86) { // x86
resolveIntel(false);
} else if (languageId.startsWith("x86") && pointerSize == POINTER_SIZE_X64) { // x86_64
resolveIntel(true);
} else { // Print an error message if the architecture is not supported
printerr("Unsupported architecture: " + languageId);
return;
}
// Print the total number of recovered strings
println("Total number of recovered dynamic strings: " + stringCount);
}
/**
* A wrapper function for the
* {@link ghidra.app.script.GhidraScript#println(String)} which is only called
* if the {@link #ENABLE_LOGGING} is <code>true</code>. The logging that is
* (potentially) passing through this function, is meant as optional logging.
* The final conclusion, as well as the logging of any error messages, should be
* printed via direct calls. The easy-to-omit nature of optional messages speeds
* up automated analysis by limiting the number of print calls.
*
* @param message
*/
private void log(String message) {
if (ENABLE_LOGGING) {
println(message);
}
}
/**
* Creates an ASCII string at the given address with the given length, and
* returns the instruction after the given instruction
*
* @param instruction the current instruction within the program
* @param address the address of the ASCII string
* @param length the length of the ASCII string
* @return the instruction after the instruction variable, or null if there is
* no such instruction
*/
private Instruction createString(Instruction instruction, Address address, Integer length) {
try {
//Get the data' starting point
Data checkData = getDataContaining(address);
if (checkData != null) {
clearListing(address);
}
// Create the ASCII string at the given address with the given length
Data data = createAsciiString(address, length);
// Gets the newly created string as a String object
String ascii = (String) data.getValue();
// Optionally print the address (clickable in Ghidra's console) along with the
// value
log("0x" + Long.toHexString(address.getOffset()) + " : \"" + ascii + "\"");
// Increment the number of recovered dynamic strings
stringCount++;
} catch (Exception ex) {
// Ignore exceptions
}
// Return the next instruction
return getInstructionAfter(instruction);
}
/**
* This helper function returns the integer value of a scalar object. The
* purpose of this function is to avoid repeated casting in numerous places
* within the script.
*
* @param scalar the object to get the integer value from
* @return the integer value of the given scalar object
*/
private Integer getInteger(Scalar scalar) {
return ((Long) scalar.getValue()).intValue();
}
/**
* Gets all memory blocks which have a name equal to .text or __text (used in PE
* and ELF, and Mach-O files respectively), disregarding the used casing. The
* list can be empty, but never null.
*
* @return all .text or __text named memory blocks (used in PE and ELF, and
* Mach-O files respectively), disregarding the used casing
*/
private List<MemoryBlock> getTextMemoryBlocks() {
// Declare and initialise the list
List<MemoryBlock> blocks = new ArrayList<>();
// Iterate over all blocks
for (MemoryBlock block : getMemoryBlocks()) {
// Check if the name is equal, disregarding the case
if (block.getName().equalsIgnoreCase(".text") || block.getName().equalsIgnoreCase("__text")) {
// If it is equal, add it to the list
blocks.add(block);
}
}
// Return the list, which might be empty
return blocks;
}
/**
* Resolves the dynamic strings for Intel architecture based binaries. This
* works for both x86 and x86_64 architectures
*
* @param is64Bit true if the given binary is 64-bit, false if not
*/
private void resolveIntel(boolean is64Bit) {
// Iterate over all memory blocks
for (MemoryBlock block : getTextMemoryBlocks()) {
// Get the first instruction from this block
Instruction instruction = getInstructionAt(block.getStart());
// Loop as long as an instruction is present and valid
while (instruction != null) {
// Check if the script's execution is cancelled
if (monitor.isCancelled()) {
// Return from the recovery function, thus exiting the script's execution early
return;
}
try {
// Get the operand type at index 1, which should be an address
int operandType = instruction.getOperandType(1);
// Get the register at index zero
Register register = instruction.getRegister(0);
/*
* Check the first instruction of a dynamically allocated string:
*
* LEA REG, [STRING_ADDRESS]
*
* This is the same for x86 and x86_64, hence no bitness check
*/
if (instruction.getMnemonicString().equalsIgnoreCase("LEA") == false || register == null
|| OperandType.isAddress(operandType) == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the next instruction
Instruction instructionTwo = getInstructionAfter(instruction);
/*
* Check the second instruction:
*
* MOV [SP + ..], REG
*
* Note that the stack pointer is either ESP or RSP, depending on the
* architecture (x86 or x86_64 respectively)
*
* Also note that REG refers to the same register as the first instruction used
*
* The is64Bit boolean is true if the used architecture is x86_64, false if it
* is x86
*/
if (instructionTwo.getMnemonicString().equalsIgnoreCase("MOV") == false
|| instructionTwo.getRegister(1) != register) {
if ((is64Bit == false
&& instructionTwo.getOpObjects(0)[0].toString().equalsIgnoreCase("ESP") == false)
|| (is64Bit == true && instructionTwo.getOpObjects(0)[0].toString()
.equalsIgnoreCase("RSP") == false)) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
}
// Get the third instruction
Instruction instructionThree = getInstructionAfter(instructionTwo);
/*
* Get the operand type (should be a scalar) at index one of the third
* instruction
*/
operandType = instructionThree.getOperandType(1);
/*
* Look for the third instruction, which follows either of the following
* patterns, depending on the architecture:
*
* MOV [ESP + ..], STRING_SIZE
*
* MOV [RSP + ..], STRING_SIZE
*
* Note that the operand type should be of the scalar type
*
* The is64Bit boolean is true if the used architecture is x86_64, false if it
* is x86
*/
if (instructionThree.getMnemonicString().equalsIgnoreCase("MOV") == false
|| OperandType.isScalar(operandType) == false) {
if ((is64Bit == false
&& instructionThree.getOpObjects(0)[0].toString().equalsIgnoreCase("ESP") == false)
|| (is64Bit == true && instructionThree.getOpObjects(0)[0].toString()
.equalsIgnoreCase("RSP") == false)) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
}
// Get the address
Address address = instruction.getPrimaryReference(1).getToAddress();
/*
* Get the instruction's first indexed object, of which the first element (index
* 0) is used
*/
Object object = instructionThree.getOpObjects(1)[0];
// Check if the object is of the scalar type
if (object instanceof Scalar == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
/*
* This code can only be reached if the object's type is scalar, so it can
* safely be cast
*/
Scalar scalar = (Scalar) object;
// Get the integer value of the scalar object
Integer lengthValue = getInteger(scalar);
/*
* Create a string at the given address with the given length, and increment to
* the next instruction
*/
instruction = createString(instruction, address, lengthValue);
} catch (Exception ex) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
}
}
}
/**
* Resolves the dynamic strings for 32-bit ARM architecture based binaries
*/
private void resolve32BitArm() {
/*
* #ARM, 32-bit
*
* #LDR REG, [STRING_ADDRESS_POINTER]
*
* #STR REG, [SP, ..]
*
* #MOV REG, STRING_SIZE
*
* #STR REG, [SP, ..]
*/
// Iterate over all memory blocks
for (MemoryBlock block : getTextMemoryBlocks()) {
// Get the first instruction
Instruction instruction = getInstructionAt(block.getStart());
// Loop as long as an instruction is present and valid
while (instruction != null) {
// Check if the script's execution is cancelled
if (monitor.isCancelled()) {
// Return from the recovery function, thus exiting the script's execution early
return;
}
try {
// Get the operand type, which should be an address or a scalar
int operandType = instruction.getOperandType(1);
// Check first instruction: LDR REG, [STRING_ADDRESS_POINTER]
if (instruction.getMnemonicString().equalsIgnoreCase("ldr") == false
|| instruction.getRegister(0) == null || OperandType.isAddress(operandType) == false
|| OperandType.isScalar(operandType) == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the register at index 0
Register register = instruction.getRegister(0);
// Get the second instruction
Instruction instructionTwo = getInstructionAfter(instruction);
/*
* Check second instruction:
*
* STR REG, [SP + ..]
*
* Note that the register REG should be the same as the register that was used
* in the first instruction
*/
if (instructionTwo.getMnemonicString().equalsIgnoreCase("str") == false
|| instructionTwo.getRegister(0) != register
|| instructionTwo.getOpObjects(1)[0].toString().equalsIgnoreCase("sp") == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the third instruction
Instruction instructionThree = getInstructionAfter(instructionTwo);
// Get the operand type, which should be a scalar
operandType = instructionThree.getOperandType(1);
// Check third instruction: MOV REG, STRING_SIZE
if (instructionThree.getMnemonicString().equalsIgnoreCase("mov") == false
|| instructionThree.getRegister(0) == null || OperandType.isScalar(operandType) == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the first register from the third instruction
register = instructionThree.getRegister(0);
// Get the first instruction
Instruction instructionFour = getInstructionAfter(instructionThree);
/*
* Check fourth instruction:
*
* STR REG, [SP + ..]
*
* Note that the register REG should be the same register that was used in the
* third instruction
*/
if (instructionFour.getMnemonicString().equalsIgnoreCase("str") == false
|| instructionFour.getRegister(0) != register
|| instructionFour.getOpObjects(1)[0].toString().equalsIgnoreCase("sp") == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the address pointer
int addressPointer = getInt(instruction.getPrimaryReference(1).getToAddress());
// Get the address, essentially dereferencing the pointer
Address address = currentProgram.getAddressFactory().getAddress(Long.toHexString(addressPointer));
// Get the second object (index 1) from the third instruction
Object object = instructionThree.getOpObjects(1)[0];
// Check if the object is of the scalar type
if (object instanceof Scalar == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
/*
* This code is only reachable if the object is of the scalar type, so it can be
* cast
*/
Scalar scalar = (Scalar) object;
// Get the scalar's value as an integer
Integer length = getInteger(scalar);
/*
* Create the ASCII string at the given address for the given length, along with
* the next instruction
*/
instruction = createString(instruction, address, length);
} catch (Exception ex) {
// Ignore exceptions
}
}
}
}
/*
* Resolves the dynamic strings for 64-bit ARM architecture based binaries
*/
private void resolve64BitArm() {
/*
* #ARM, 64-bit - version 1
*
* #ADRP REG, [STRING_ADDRESS_START]
*
* #ADD REG, REG, INT
*
* #STR REG, [SP, ..]
*
* #ORR REG, REG, STRING_SIZE
*
* #STR REG, [SP, ..]
*
* #ARM, 64-bit - version 2
*
* #ADRP REG, [STRING_ADDRESS_START]
*
* #ADD REG, REG, INT
*
* #STR REG, [SP, ..]
*
* #MOV REG, STRING_SIZE
*
* #STR REG, [SP, ..]
*/
// Iterate over all memory blocks
for (MemoryBlock block : getTextMemoryBlocks()) {
// Get the first instruction from this block
Instruction instruction = getInstructionAt(block.getStart());
// Loop as long as an instruction is present and valid
while (instruction != null) {
// Check if the script's execution is cancelled
if (monitor.isCancelled()) {
// Return from the recovery function, thus exiting the script's execution early
return;
}
// Get the operand type at index 1, which should be a scalar
int operandType = instruction.getOperandType(1);
// Get the register at index zero
Register register = instruction.getRegister(0);
/*
* Check first instruction of a dynamically allocated string
*
* ADRP REG, [STRING_ADDRESS_START]
*/
if (instruction.getMnemonicString().equalsIgnoreCase("adrp") == false
|| instruction.getRegister(0) == null || OperandType.isAddress(operandType) == false
|| OperandType.isScalar(operandType) == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the second instruction
Instruction instructionTwo = getInstructionAfter(instruction);
/*
* Get the operand type of the second instruction at index 2, which should be of
* the scalar type
*/
operandType = instructionTwo.getOperandType(2);
/*
* Check second instruction:
*
* ADD REG, REG, INT
*
* Note that REG refers to the same register as the first instruction used
*
* Also note that the operand type needs to be of the scalar type
*/
if (instructionTwo.getMnemonicString().equalsIgnoreCase("add") == false
|| instructionTwo.getRegister(0) != register || OperandType.isScalar(operandType) == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the third instruction
Instruction instructionThree = getInstructionAfter(instructionTwo);
/*
* Check the third instruction:
*
* STR REG, [SP + ..]
*
* Note that REG refers to the same register as the first instruction used
*/
if (instructionThree.getMnemonicString().equalsIgnoreCase("str") == false
|| instructionThree.getRegister(0) != register
|| instructionThree.getOpObjects(1)[0].toString().equalsIgnoreCase("sp") == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get the fourth instruction
Instruction instructionFour = getInstructionAfter(instructionThree);
// Get the register from the fourth instruction, at index 0
register = instructionFour.getRegister(0);
/*
* Declare several variables, which are to be initialised at a later stage,
* depending on the way it is loaded (version 1 or version 2)
*/
int length;
Object object;
Scalar scalar;
/*
* Check fourth instruction:
*
* Version 1: ORR REG, REG, STRING_SIZE
*
* Version 2: MOV REG, STRING_SIZE
*
* Note that the operand type needs to be a scalar
*
* Also note that the register from the fourth instruction should not be null
*/
if (instructionFour.getMnemonicString().equalsIgnoreCase("orr") == false && register != null
&& OperandType.isScalar(instructionFour.getOperandType(2)) == true) {
// Get the relevant object
object = instructionFour.getOpObjects(2)[0];
/*
* The relevant object is of the scalar type, as defined within the if-statement
*/
scalar = (Scalar) object;
// Get the scalar's value as an integer
length = getInteger(scalar);
} else if (instructionFour.getMnemonicString().equalsIgnoreCase("mov") && register != null
&& OperandType.isScalar(instructionFour.getOperandType(1)) == true) {
// Get the relevant object
object = instructionFour.getOpObjects(1)[0];
/*
* The relevant object is of the scalar type, as defined within the if-statement
*/
scalar = (Scalar) object;
// Get the scalar's value as an integer
length = getInteger(scalar);
} else {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Gets the fifth instruction
Instruction instructionFive = getInstructionAfter(instructionFour);
/*
* Check fifth instruction:
*
* STR REG, [SP + ..]
*
* Note that REG refers to the same register as the fourth instruction used
*/
if (instructionFive.getMnemonicString().equalsIgnoreCase("str") == false
|| instructionFive.getRegister(0) != register
|| instructionFive.getOpObjects(1)[0].toString().equalsIgnoreCase("sp") == false) {
// Get the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Get two objects
Object objA = instruction.getOpObjects(1)[0];
Object objB = instructionTwo.getOpObjects(2)[0];
// Ensure that both objects are of the scalar type
if (objA instanceof Scalar == false || objB instanceof Scalar == false) {
// Gets the next instruction
instruction = getInstructionAfter(instruction);
// Skip this item in the loop
continue;
}
// Cast the object to the correct type if this code is reached
scalar = (Scalar) objA;
// Get the scalar's value as an integer
Integer addressPointer = getInteger(scalar);
// Cast the object to the correct type if this code is reached
scalar = (Scalar) objB;
/*
* Get the scalar's value as an integer. Note the "+=" instead of "="
*/
addressPointer += getInteger(scalar);
// Dereference the pointer
Address address = currentProgram.getAddressFactory().getAddress(Long.toHexString(addressPointer));
/*
* Create the ASCII string at the given address for the given length, along with
* the next instruction
*/
instruction = createString(instruction, address, length);
}
}
}
}