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Qualys 安全公告:OpenSSH 存在两个新漏洞

Qualys 安全团队近期发现了 OpenSSH 中的两个新漏洞,分别涉及中间人攻击(MitM)和拒绝服务攻击(DoS)。以下是漏洞的详细说明:

1. CVE-2025-26465:OpenSSH 客户端中间人攻击漏洞
- 当 OpenSSH 客户端的 VerifyHostKeyDNS 选项启用时(默认关闭),攻击者可以通过中间人攻击完全绕过客户端对服务器身份的验证,从而冒充服务器。
- 无论 VerifyHostKeyDNS 设置为 "yes" 还是 "ask"(默认是 "no"),攻击都能成功,且无需用户交互。即使服务器没有 SSHFP 资源记录(存储在 DNS 中的 SSH 指纹),攻击依然有效。
- 该漏洞于 2014 年 12 月引入,影响范围广泛。尽管默认情况下 VerifyHostKeyDNS 是关闭的,但在某些系统(如 FreeBSD)中,该选项曾默认启用。

2. CVE-2025-26466:OpenSSH 客户端和服务器的拒绝服务攻击漏洞
- OpenSSH 客户端和服务器在认证前容易受到资源消耗型拒绝服务攻击,攻击者可以消耗大量内存和 CPU 资源。
- 该漏洞于 2023 年 8 月引入,影响 OpenSSH 9.5p1 及之后的版本。
- 服务器端可以通过现有的机制(如 LoginGraceTimeMaxStartupsPerSourcePenalties)缓解此攻击。

背景信息:
OpenSSH 的代码中存在一些常见的编程模式,例如在函数开始时初始化返回值为非零错误代码,以防止函数错误地返回成功状态。这种模式在漏洞分析中被发现存在潜在风险。

建议:
- 对于 CVE-2025-26465,建议用户检查并确保 VerifyHostKeyDNS 选项未启用,除非有明确需求。
- 对于 CVE-2025-26466,建议更新到最新版本的 OpenSSH,并配置适当的防护机制。

更多详细信息请参考:
- [OpenSSH 文档](https://man.openbsd.org/ssh_config#VerifyHostKeyDNS)
- [FreeBSD 相关提交记录](https://cgit.freebsd.org/src/commit/?id=83c6a52)

#网络安全 #OpenSSH #漏洞 #中间人攻击 #拒绝服务攻击
#AIGC



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Qualys 安全公告:OpenSSH 存在两个新漏洞

Qualys 安全团队近期发现了 OpenSSH 中的两个新漏洞,分别涉及中间人攻击(MitM)和拒绝服务攻击(DoS)。以下是漏洞的详细说明:

1. CVE-2025-26465:OpenSSH 客户端中间人攻击漏洞
- 当 OpenSSH 客户端的 VerifyHostKeyDNS 选项启用时(默认关闭),攻击者可以通过中间人攻击完全绕过客户端对服务器身份的验证,从而冒充服务器。
- 无论 VerifyHostKeyDNS 设置为 "yes" 还是 "ask"(默认是 "no"),攻击都能成功,且无需用户交互。即使服务器没有 SSHFP 资源记录(存储在 DNS 中的 SSH 指纹),攻击依然有效。
- 该漏洞于 2014 年 12 月引入,影响范围广泛。尽管默认情况下 VerifyHostKeyDNS 是关闭的,但在某些系统(如 FreeBSD)中,该选项曾默认启用。

2. CVE-2025-26466:OpenSSH 客户端和服务器的拒绝服务攻击漏洞
- OpenSSH 客户端和服务器在认证前容易受到资源消耗型拒绝服务攻击,攻击者可以消耗大量内存和 CPU 资源。
- 该漏洞于 2023 年 8 月引入,影响 OpenSSH 9.5p1 及之后的版本。
- 服务器端可以通过现有的机制(如 LoginGraceTimeMaxStartupsPerSourcePenalties)缓解此攻击。

背景信息:
OpenSSH 的代码中存在一些常见的编程模式,例如在函数开始时初始化返回值为非零错误代码,以防止函数错误地返回成功状态。这种模式在漏洞分析中被发现存在潜在风险。

建议:
- 对于 CVE-2025-26465,建议用户检查并确保 VerifyHostKeyDNS 选项未启用,除非有明确需求。
- 对于 CVE-2025-26466,建议更新到最新版本的 OpenSSH,并配置适当的防护机制。

更多详细信息请参考:
- [OpenSSH 文档](https://man.openbsd.org/ssh_config#VerifyHostKeyDNS)
- [FreeBSD 相关提交记录](https://cgit.freebsd.org/src/commit/?id=83c6a52)

#网络安全 #OpenSSH #漏洞 #中间人攻击 #拒绝服务攻击
#AIGC

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Although some channels have been removed, the curation process is considered opaque and insufficient by analysts. The SC urges the public to refer to the SC’s I nvestor Alert List before investing. The list contains details of unauthorised websites, investment products, companies and individuals. Members of the public who suspect that they have been approached by unauthorised firms or individuals offering schemes that promise unrealistic returns Since its launch in 2013, Telegram has grown from a simple messaging app to a broadcast network. Its user base isn’t as vast as WhatsApp’s, and its broadcast platform is a fraction the size of Twitter, but it’s nonetheless showing its use. While Telegram has been embroiled in controversy for much of its life, it has become a vital source of communication during the invasion of Ukraine. But, if all of this is new to you, let us explain, dear friends, what on Earth a Telegram is meant to be, and why you should, or should not, need to care. After fleeing Russia, the brothers founded Telegram as a way to communicate outside the Kremlin's orbit. They now run it from Dubai, and Pavel Durov says it has more than 500 million monthly active users. Channels are not fully encrypted, end-to-end. All communications on a Telegram channel can be seen by anyone on the channel and are also visible to Telegram. Telegram may be asked by a government to hand over the communications from a channel. Telegram has a history of standing up to Russian government requests for data, but how comfortable you are relying on that history to predict future behavior is up to you. Because Telegram has this data, it may also be stolen by hackers or leaked by an internal employee.
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