From 18c59c32a09074c1a1883226c816d756888884db Mon Sep 17 00:00:00 2001 From: Peter Korsgaard Date: Mon, 12 Jul 2021 23:03:07 +0200 Subject: [PATCH] package/tpm2-tools: backport CVE-2021-3565 security fix Fixes CVE-2021-3565: A flaw was found in tpm2-tools in versions before 5.1.1 and before 4.3.2. tpm2_import used a fixed AES key for the inner wrapper, potentially allowing a MITM attacker to unwrap the inner portion and reveal the key being imported. The highest threat from this vulnerability is to data confidentiality. Signed-off-by: Peter Korsgaard --- ...port-fix-fixed-AES-key-CVE-2021-3565.patch | 47 +++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 package/tpm2-tools/0001-tpm2_import-fix-fixed-AES-key-CVE-2021-3565.patch diff --git a/package/tpm2-tools/0001-tpm2_import-fix-fixed-AES-key-CVE-2021-3565.patch b/package/tpm2-tools/0001-tpm2_import-fix-fixed-AES-key-CVE-2021-3565.patch new file mode 100644 index 0000000000..c0a433251f --- /dev/null +++ b/package/tpm2-tools/0001-tpm2_import-fix-fixed-AES-key-CVE-2021-3565.patch @@ -0,0 +1,47 @@ +From c069e4f179d5e6653a84fb236816c375dca82515 Mon Sep 17 00:00:00 2001 +From: William Roberts +Date: Fri, 21 May 2021 12:22:31 -0500 +Subject: [PATCH] tpm2_import: fix fixed AES key CVE-2021-3565 + +tpm2_import used a fixed AES key for the inner wrapper, which means that +a MITM attack would be able to unwrap the imported key. Even the +use of an encrypted session will not prevent this. The TPM only +encrypts the first parameter which is the fixed symmetric key. + +To fix this, ensure the key size is 16 bytes or bigger and use +OpenSSL to generate a secure random AES key. + +Fixes: #2738 + +Signed-off-by: William Roberts +Signed-off-by: Peter Korsgaard +--- + tools/tpm2_import.c | 12 +++++++++++- + 1 file changed, 11 insertions(+), 1 deletion(-) + +diff --git a/tools/tpm2_import.c b/tools/tpm2_import.c +index cfb6f207..f44326c8 100644 +--- a/tools/tpm2_import.c ++++ b/tools/tpm2_import.c +@@ -118,7 +118,17 @@ static tool_rc key_import(ESYS_CONTEXT *ectx, TPM2B_PUBLIC *parent_pub, + TPM2B_DATA enc_sensitive_key = { + .size = parent_pub->publicArea.parameters.rsaDetail.symmetric.keyBits.sym / 8 + }; +- memset(enc_sensitive_key.buffer, 0xFF, enc_sensitive_key.size); ++ ++ if(enc_sensitive_key.size < 16) { ++ LOG_ERR("Calculated wrapping keysize is less than 16 bytes, got: %u", enc_sensitive_key.size); ++ return tool_rc_general_error; ++ } ++ ++ int ossl_rc = RAND_bytes(enc_sensitive_key.buffer, enc_sensitive_key.size); ++ if (ossl_rc != 1) { ++ LOG_ERR("RAND_bytes failed: %s", ERR_error_string(ERR_get_error(), NULL)); ++ return tool_rc_general_error; ++ } + + /* + * Calculate the object name. +-- +2.20.1 +