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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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But Telegram says people want to keep their chat history when they get a new phone, and they like having a data backup that will sync their chats across multiple devices. And that is why they let people choose whether they want their messages to be encrypted or not. When not turned on, though, chats are stored on Telegram's services, which are scattered throughout the world. But it has "disclosed 0 bytes of user data to third parties, including governments," Telegram states on its website. Recently, Durav wrote on his Telegram channel that users' right to privacy, in light of the war in Ukraine, is "sacred, now more than ever." Unlike Silicon Valley giants such as Facebook and Twitter, which run very public anti-disinformation programs, Brooking said: "Telegram is famously lax or absent in its content moderation policy." This ability to mix the public and the private, as well as the ability to use bots to engage with users has proved to be problematic. In early 2021, a database selling phone numbers pulled from Facebook was selling numbers for $20 per lookup. Similarly, security researchers found a network of deepfake bots on the platform that were generating images of people submitted by users to create non-consensual imagery, some of which involved children. Telegram does offer end-to-end encrypted communications through Secret Chats, but this is not the default setting. Standard conversations use the MTProto method, enabling server-client encryption but with them stored on the server for ease-of-access. This makes using Telegram across multiple devices simple, but also means that the regular Telegram chats you’re having with folks are not as secure as you may believe.
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