SynopsisThe remote web server is running an outdated instance of OpenSSL and thus may be missing patches for multiple vulnerabilities.
DescriptionVersions of OpenSSL prior to 1.0.1n, or 1.0.2b are unpatched for the following vulnerabilities :
- A man-in-the-middle vulnerability, known as Logjam, exists due to a flaw in the SSL/TLS protocol. A remote attacker can exploit this flaw to downgrade connections using ephemeral Diffie-Hellman key exchange to 512-bit export-grade cryptography. (CVE-2015-4000)
- A denial of service vulnerability exists when processing an ECParameters structure due to an infinite loop that occurs when a specified curve is over a malformed binary polynomial field. A remote attacker can exploit this to perform a denial of service against any system that processes public keys, certificate requests, or certificates. This includes TLS clients and TLS servers with client authentication enabled. (CVE-2015-1788)
- A denial of service vulnerability exists due to improper validation of the content and length of the ASN1_TIME string by the X509_cmp_time() function. A remote attacker can exploit this, via a malformed certificate and CRLs of various sizes, to cause a segmentation fault, resulting in a denial of service condition. TLS clients that verify CRLs are affected. TLS clients and servers with client authentication enabled may be affected if they use custom verification callbacks. (CVE-2015-1789)
- A NULL pointer dereference flaw exists in the PKCS#7 parsing code due to incorrect handling of missing inner 'EncryptedContent'. This allows a remote attacker, via specially crafted ASN.1-encoded PKCS#7 blobs with missing content, to cause a denial of service condition or other potential unspecified impacts. (CVE-2015-1790)
- A double-free error exists due to a race condition that occurs when a NewSessionTicket is received by a multi-threaded client when attempting to reuse a previous ticket. (CVE-2015-1791)
- A denial of service vulnerability exists in the CMS code due to an infinite loop that occurs when verifying a signedData message. A remote attacker can exploit this to cause a denial of service condition. (CVE-2015-1792)
- An off-by-one overflow condition affects the BN_rand() function in 'crypto/bn/random.c'. The issue is triggered as user-supplied input is not properly validated. This may allow an attacker to cause a buffer overflow, resulting in a denial of service.
- An off-by-one overflow condition affects the BN_bn2hex() function in 'crypto/bn/bn_print.c'. The issue is triggered as user-supplied input is not properly validated. This may allow an attacker to cause a buffer overflow, potentially resulting in a denial of service or another, more severe impact.
SolutionOpenSSL versions 1.0.1n and 1.0.2b are patched against these vulnerabilities. Apply the vendors patch, or update to these versions or later.