Subject: Fix potential DoS issue with p2c header
ID: CVE-2023-50967
Origin: v12-3-g4ee7708 <https://github.com/latchset/jose/commit/v12-3-g4ee7708>
Upstream-Author: Sergio Correia <scorreia@redhat.com>
Date: Mon Apr 1 12:10:54 2024 +0100

    Unbounded p2c headers may be used to cause an application that accept
    PBES algorithms to spend a lot of resources running PBKDF2 with a very
    high number of iterations.

    Limit the maximum number of iterations to to 32768.

    Fixes: CVE-2023-50967

    Signed-off-by: Sergio Correia <scorreia@redhat.com>

--- a/lib/openssl/pbes2.c
+++ b/lib/openssl/pbes2.c
@@ -25,6 +25,8 @@
 #include <string.h>
 
 #define NAMES "PBES2-HS256+A128KW", "PBES2-HS384+A192KW", "PBES2-HS512+A256KW"
+#define P2C_MIN_ITERATIONS 1000
+#define P2C_MAX_ITERATIONS 32768
 
 static json_t *
 pbkdf2(const char *alg, jose_cfg_t *cfg, const json_t *jwk, int iter,
@@ -170,7 +172,7 @@
     json_auto_t *hdr = NULL;
     const char *aes = NULL;
     json_t *h = NULL;
-    int p2c = 10000;
+    int p2c = P2C_MAX_ITERATIONS;
     size_t stl = 0;
 
     if (!json_object_get(cek, "k") && !jose_jwk_gen(cfg, cek))
@@ -203,7 +205,7 @@
         json_object_set_new(h, "p2c", json_integer(p2c)) < 0)
         return false;
 
-    if (p2c < 1000)
+    if (p2c < P2C_MIN_ITERATIONS || p2c > P2C_MAX_ITERATIONS)
         return false;
 
     if (json_object_set_new(h, "p2s", jose_b64_enc(st, stl)) == -1)
@@ -245,6 +247,9 @@
     if (json_unpack(hdr, "{s:I}", "p2c", &p2c) == -1)
         return false;
 
+    if (p2c > P2C_MAX_ITERATIONS)
+        return false;
+
     stl = jose_b64_dec(json_object_get(hdr, "p2s"), NULL, 0);
     if (stl < 8 || stl > sizeof(st))
         return false;
--- /dev/null
+++ b/tests/cve-2023-50967/cve-2023-50967.jwe
@@ -0,0 +1 @@
+{"ciphertext":"aaPb-JYGACs-loPwJkZewg","encrypted_key":"P1h8q8wLVxqYsZUuw6iEQTzgXVZHCsu8Eik-oqbE4AJGIDto3gb3SA","header":{"alg":"PBES2-HS256+A128KW","p2c":1000000000,"p2s":"qUQQWWkyyIqculSiC93mlg"},"iv":"Clg3JX9oNl_ck3sLSGrlgg","protected":"eyJlbmMiOiJBMTI4Q0JDLUhTMjU2In0","tag":"i7vga9tJkwRswFd7HlyD_A"}
--- /dev/null
+++ b/tests/cve-2023-50967/cve-2023-50967.jwk
@@ -0,0 +1 @@
+{"alg":"PBES2-HS256+A128KW","k":"VHBLJ4-PmnqELoKbQoXuRA","key_ops":["wrapKey","unwrapKey"],"kty":"oct"}
--- a/tests/jose-jwe-dec
+++ b/tests/jose-jwe-dec
@@ -53,3 +53,8 @@
 test "`jose jwe dec -i $prfx.13.jweg -k $prfx.13.1.jwk`" == "`cat $prfx.13.pt`"
 test "`jose jwe dec -i $prfx.13.jweg -k $prfx.13.2.jwk`" == "`cat $prfx.13.pt`"
 test "`jose jwe dec -i $prfx.13.jweg -k $prfx.13.3.jwk`" == "`cat $prfx.13.pt`"
+
+# CVE-2023-50967 - test originally from https://github.com/P3ngu1nW/CVE_Request/blob/main/latch-jose.md
+# This test is expected to fail quickly on patched systems.
+prfx="${CVE_2023_50967}/cve-2023-50967"
+! test "$(jose jwe dec -i $prfx.jwe -k $prfx.jwk)"
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -2,7 +2,8 @@
 LDFLAGS += $(top_builddir)/lib/libjose.la @jansson_LIBS@
 EXTRA_DIST = vectors
 
-AM_TESTS_ENVIRONMENT=PATH=$(top_builddir)/cmd:$(PATH) VECTORS=$(top_srcdir)/tests/vectors
+AM_TESTS_ENVIRONMENT=PATH=$(top_builddir)/cmd:$(PATH) VECTORS=$(top_srcdir)/tests/vectors CVE_2023_50967=$(top_srcdir)/tests/cve-2023-50967
+
 TESTS = $(dist_check_SCRIPTS) $(check_PROGRAMS)
 
 check_PROGRAMS = \