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CVE-2021-23839— OpenSSL 加密问题漏洞

一分钟漏洞结论

影响对象
OpenSSL OpenSSL
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。

OpenSSL是Openssl团队的一个开源的能够实现安全套接层（SSLv2/v3）和安全传输层（TLSv1）协议的通用加密库。该产品支持多种加密算法，包括对称密码、哈希算法、安全散列算法等。 OpenSSL 1.0.2 存在加密问题漏洞，该漏洞源于在解除填充RSA签名时，将对版本回滚攻击进行检查。

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一、 漏洞 CVE-2021-23839 基础信息

漏洞信息
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Vulnerability Title
Incorrect SSLv2 rollback protection
来源: CVE Program / CVE List V5
Vulnerability Description
OpenSSL 1.0.2 supports SSLv2. If a client attempts to negotiate SSLv2 with a server that is configured to support both SSLv2 and more recent SSL and TLS versions then a check is made for a version rollback attack when unpadding an RSA signature. Clients that support SSL or TLS versions greater than SSLv2 are supposed to use a special form of padding. A server that supports greater than SSLv2 is supposed to reject connection attempts from a client where this special form of padding is present, because this indicates that a version rollback has occurred (i.e. both client and server support greater than SSLv2, and yet this is the version that is being requested). The implementation of this padding check inverted the logic so that the connection attempt is accepted if the padding is present, and rejected if it is absent. This means that such as server will accept a connection if a version rollback attack has occurred. Further the server will erroneously reject a connection if a normal SSLv2 connection attempt is made. Only OpenSSL 1.0.2 servers from version 1.0.2s to 1.0.2x are affected by this issue. In order to be vulnerable a 1.0.2 server must: 1) have configured SSLv2 support at compile time (this is off by default), 2) have configured SSLv2 support at runtime (this is off by default), 3) have configured SSLv2 ciphersuites (these are not in the default ciphersuite list) OpenSSL 1.1.1 does not have SSLv2 support and therefore is not vulnerable to this issue. The underlying error is in the implementation of the RSA_padding_check_SSLv23() function. This also affects the RSA_SSLV23_PADDING padding mode used by various other functions. Although 1.1.1 does not support SSLv2 the RSA_padding_check_SSLv23() function still exists, as does the RSA_SSLV23_PADDING padding mode. Applications that directly call that function or use that padding mode will encounter this issue. However since there is no support for the SSLv2 protocol in 1.1.1 this is considered a bug and not a security issue in that version. OpenSSL 1.0.2 is out of support and no longer receiving public updates. Premium support customers of OpenSSL 1.0.2 should upgrade to 1.0.2y. Other users should upgrade to 1.1.1j. Fixed in OpenSSL 1.0.2y (Affected 1.0.2s-1.0.2x).
来源: CVE Program / CVE List V5
CVSS Information
N/A
来源: CVE Program / CVE List V5
Vulnerability Type
N/A
来源: CVE Program / CVE List V5
Vulnerability Title
OpenSSL 加密问题漏洞
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Description
OpenSSL是Openssl团队的一个开源的能够实现安全套接层（SSLv2/v3）和安全传输层（TLSv1）协议的通用加密库。该产品支持多种加密算法，包括对称密码、哈希算法、安全散列算法等。 OpenSSL 1.0.2 存在加密问题漏洞，该漏洞源于在解除填充RSA签名时，将对版本回滚攻击进行检查。
来源: 中国国家信息安全漏洞库 CNNVD
CVSS Information
N/A
来源: 中国国家信息安全漏洞库 CNNVD
Vulnerability Type
N/A
来源: 中国国家信息安全漏洞库 CNNVD

受影响产品

厂商 产品 影响版本 CPE 订阅
OpenSSL OpenSSL Fixed in OpenSSL 1.0.2y (Affected 1.0.2s-1.0.2x) -

二、漏洞 CVE-2021-23839 的公开POC

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三、漏洞 CVE-2021-23839 的情报信息

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CVE-2021-23839 厂商安全公告 (8)

CVE-2021-23839 其他参考 (1)

同批安全公告 · OpenSSL · 2021-02-16 · 共 3 条

CVE-2021-23841 OpenSSL 代码问题漏洞
CVE-2021-23840 OpenSSL 输入验证错误漏洞

IV. Related Vulnerabilities

Same product: OpenSSL
Same vendor: OpenSSL

V. Comments for CVE-2021-23839

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