1 files changed, 155 insertions, 0 deletions

diff --git a/other/openssh-reverse/deattack.c b/other/openssh-reverse/deattack.c
new file mode 100644
index 0000000..7f95eca
--- /dev/null
+++ b/other/openssh-reverse/deattack.c
@@ -0,0 +1,155 @@
+/*
+ * $OpenBSD: deattack.c,v 1.7 2000/06/20 01:39:41 markus Exp $
+ * Cryptographic attack detector for ssh - source code
+ *
+ * Copyright (c) 1998 CORE SDI S.A., Buenos Aires, Argentina.
+ *
+ * All rights reserved. Redistribution and use in source and binary
+ * forms, with or without modification, are permitted provided that
+ * this copyright notice is retained.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
+ * WARRANTIES ARE DISCLAIMED. IN NO EVENT SHALL CORE SDI S.A. BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY OR
+ * CONSEQUENTIAL DAMAGES RESULTING FROM THE USE OR MISUSE OF THIS
+ * SOFTWARE.
+ *
+ * Ariel Futoransky <futo@core-sdi.com>
+ * <http://www.core-sdi.com>
+ */
+
+#include "includes.h"
+#include "deattack.h"
+#include "ssh.h"
+#include "crc32.h"
+#include "getput.h"
+#include "xmalloc.h"
+
+/* SSH Constants */
+#define SSH_MAXBLOCKS   (32 * 1024)
+#define SSH_BLOCKSIZE   (8)
+
+/* Hashing constants */
+#define HASH_MINSIZE    (8 * 1024)
+#define HASH_ENTRYSIZE  (2)
+#define HASH_FACTOR(x)  ((x)*3/2)
+#define HASH_UNUSEDCHAR (0xff)
+#define HASH_UNUSED     (0xffff)
+#define HASH_IV         (0xfffe)
+
+#define HASH_MINBLOCKS  (7*SSH_BLOCKSIZE)
+
+
+/* Hash function (Input keys are cipher results) */
+#define HASH(x)         GET_32BIT(x)
+
+#define CMP(a,b)        (memcmp(a, b, SSH_BLOCKSIZE))
+
+
+void
+crc_update(u_int32_t *a, u_int32_t b)
+{
+        b ^= *a;
+        *a = crc32((unsigned char *) &b, sizeof(b));
+}
+
+/* detect if a block is used in a particular pattern */
+int
+check_crc(unsigned char *S, unsigned char *buf, u_int32_t len,
+          unsigned char *IV)
+{
+        u_int32_t crc;
+        unsigned char *c;
+
+        crc = 0;
+        if (IV && !CMP(S, IV)) {
+                crc_update(&crc, 1);
+                crc_update(&crc, 0);
+        }
+        for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
+                if (!CMP(S, c)) {
+                        crc_update(&crc, 1);
+                        crc_update(&crc, 0);
+                } else {
+                        crc_update(&crc, 0);
+                        crc_update(&crc, 0);
+                }
+        }
+        return (crc == 0);
+}
+
+
+/* Detect a crc32 compensation attack on a packet */
+int
+detect_attack(unsigned char *buf, u_int32_t len, unsigned char *IV)
+{
+        static u_int16_t *h = (u_int16_t *) NULL;
+        static u_int16_t n = HASH_MINSIZE / HASH_ENTRYSIZE;
+        register u_int32_t i, j;
+        u_int32_t l;
+        register unsigned char *c;
+        unsigned char *d;
+
+        if (len > (SSH_MAXBLOCKS * SSH_BLOCKSIZE) ||
+            len % SSH_BLOCKSIZE != 0) {
+                fatal("detect_attack: bad length %d", len);
+        }
+        for (l = n; l < HASH_FACTOR(len / SSH_BLOCKSIZE); l = l << 2)
+                ;
+
+        if (h == NULL) {
+                debug("Installing crc compensation attack detector.");
+                n = l;
+                h = (u_int16_t *) xmalloc(n * HASH_ENTRYSIZE);
+        } else {
+                if (l > n) {
+                        n = l;
+                        h = (u_int16_t *) xrealloc(h, n * HASH_ENTRYSIZE);
+                }
+        }
+
+        if (len <= HASH_MINBLOCKS) {
+                for (c = buf; c < buf + len; c += SSH_BLOCKSIZE) {
+                        if (IV && (!CMP(c, IV))) {
+                                if ((check_crc(c, buf, len, IV)))
+                                        return (DEATTACK_DETECTED);
+                                else
+                                        break;
+                        }
+                        for (d = buf; d < c; d += SSH_BLOCKSIZE) {
+                                if (!CMP(c, d)) {
+                                        if ((check_crc(c, buf, len, IV)))
+                                                return (DEATTACK_DETECTED);
+                                        else
+                                                break;
+                                }
+                        }
+                }
+                return (DEATTACK_OK);
+        }
+        memset(h, HASH_UNUSEDCHAR, n * HASH_ENTRYSIZE);
+
+        if (IV)
+                h[HASH(IV) & (n - 1)] = HASH_IV;
+
+        for (c = buf, j = 0; c < (buf + len); c += SSH_BLOCKSIZE, j++) {
+                for (i = HASH(c) & (n - 1); h[i] != HASH_UNUSED;
+                     i = (i + 1) & (n - 1)) {
+                        if (h[i] == HASH_IV) {
+                                if (!CMP(c, IV)) {
+                                        if (check_crc(c, buf, len, IV))
+                                                return (DEATTACK_DETECTED);
+                                        else
+                                                break;
+                                }
+                        } else if (!CMP(c, buf + h[i] * SSH_BLOCKSIZE)) {
+                                if (check_crc(c, buf, len, IV))
+                                        return (DEATTACK_DETECTED);
+                                else
+                                        break;
+                        }
+                }
+                h[i] = j;
+        }
+        return (DEATTACK_OK);
+}