CVE-2015-1790 (published 2015-06-12T19:59Z)

The PKCS7_dataDecodefunction in crypto/pkcs7/pk7_doit.c in OpenSSL before 0.9.8zg, 1.0.0 before 1.0.0s, 1.0.1 before 1.0.1n, and 1.0.2 before 1.0.2b allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a PKCS#7 blob that uses ASN.1 encoding and lacks inner EncryptedContent data.

Severity: MEDIUM
CVSS v2 base score: 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P)

Weakness information:
cwe_id: NVD-CWE-Other
cwe_name: Other
description: NVD is only using a subset of CWE for mapping instead of the entire CWE, and the weakness type is not covered by that subset.
extended_description: Insufficient Information

Fix information:
repo_url: https://github.com/openssl/openssl
commit_details: repo_url: https://github.com/openssl/openssl
author: Emilia Kasper
author_date: 2015-05-12 19:00:30+02:00
msg: PKCS#7: Fix NULL dereference with missing EncryptedContent.

CVE-2015-1790

Reviewed-by: Rich Salz <rsalz@openssl.org>
repository: repo_url: https://github.com/openssl/openssl
repo_name: openssl/openssl
description: TLS/SSL and crypto library
repo_language: C
owner: openssl
file_changes: filename: pk7_doit.c
change_type: ModificationType.MODIFY
diff: @@ -432,6 +432,12 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
 
     switch (i) {
     case NID_pkcs7_signed:
+        /*
+         * p7->d.sign->contents is a PKCS7 structure consisting of a contentType
+         * field and optional content.
+         * data_body is NULL if that structure has no (=detached) content
+         * or if the contentType is wrong (i.e., not "data").
+         */
         data_body = PKCS7_get_octet_string(p7->d.sign->contents);
         if (!PKCS7_is_detached(p7) && data_body == NULL) {
             PKCS7err(PKCS7_F_PKCS7_DATADECODE,
@@ -443,6 +449,7 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
     case NID_pkcs7_signedAndEnveloped:
         rsk = p7->d.signed_and_enveloped->recipientinfo;
         md_sk = p7->d.signed_and_enveloped->md_algs;
+        /* data_body is NULL if the optional EncryptedContent is missing. */
         data_body = p7->d.signed_and_enveloped->enc_data->enc_data;
         enc_alg = p7->d.signed_and_enveloped->enc_data->algorithm;
         evp_cipher = EVP_get_cipherbyobj(enc_alg->algorithm);
@@ -455,6 +462,7 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
     case NID_pkcs7_enveloped:
         rsk = p7->d.enveloped->recipientinfo;
         enc_alg = p7->d.enveloped->enc_data->algorithm;
+        /* data_body is NULL if the optional EncryptedContent is missing. */
         data_body = p7->d.enveloped->enc_data->enc_data;
         evp_cipher = EVP_get_cipherbyobj(enc_alg->algorithm);
         if (evp_cipher == NULL) {
@@ -468,6 +476,12 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
         goto err;
     }
 
+    /* Detached content must be supplied via in_bio instead. */
+    if (data_body == NULL && in_bio == NULL) {
+        PKCS7err(PKCS7_F_PKCS7_DATADECODE, PKCS7_R_NO_CONTENT);
+        goto err;
+    }
+
     /* We will be checking the signature */
     if (md_sk != NULL) {
         for (i = 0; i < sk_X509_ALGOR_num(md_sk); i++) {
@@ -593,7 +607,7 @@ BIO *PKCS7_dataDecode(PKCS7 *p7, EVP_PKEY *pkey, BIO *in_bio, X509 *pcert)
             BIO_push(out, etmp);
         etmp = NULL;
     }
-    if (PKCS7_is_detached(p7) || (in_bio != NULL)) {
+    if (in_bio != NULL) {
         bio = in_bio;
     } else {
         if (data_body->length > 0)

programming_language: C