前幾天用 Nessus 掃描自己用的筆記本, 報(bào)告有安全漏洞:
The remote service accepts connections encrypted using SSL 2.0, which reportedly suffers from several cryptographic flaws and has been deprecated for several years. An attacker may be able to exploit these issues to conduct man-in-the-middle attacks or decrypt communications between the affected service and clients
閱讀了一下推薦的文檔 Analysis of the SSL 3.0 protocol, SSL 2.0 果然存在不少問題.
其中一個(gè)問題是 SSL 2.0 容易受到密碼組回滾攻擊(CipherSuite Rollback attack). 關(guān)于 ciphersuite rollback attack:
An attack against how Secure Socket Layer version 2 (SSL v2) negotiates the cipher suite. The aim is to convince Alice and Bob to use much weaker encryption than they are capable of using.
該攻擊方法通過惡意編輯在 hello 報(bào)文中發(fā)送的所支持密碼組的明文列表而使得使用者被動(dòng)選擇弱化的出口加密算法.這幾乎是 SSL 2.0 的致命缺陷.
另外一個(gè)問題是由于美國安全產(chǎn)品出口法的限制: 只能使用不超過 40 位的 MAC( 報(bào)文驗(yàn)證碼, message authentication codes). SSl 2.0 使用 MAC 后添加字節(jié)的塊加密模式,但是添加的長(zhǎng)度字段是未經(jīng)驗(yàn)證的,這給了主動(dòng)攻擊者會(huì)刪除最后的內(nèi)容的可能.
對(duì)于 SSL V2 也可能存在中間人攻擊(man-in-the-middle attack). 雖然 Diffie-Hellman 是目前最為完美的公鑰算法．但是在 SSL V2 的缺陷使得供給者能夠巧妙偽造一個(gè)數(shù)字證書, 讓客戶以為他是和真正的服務(wù)器通訊. 在 SSL V3 中則對(duì)該缺陷進(jìn)行了改進(jìn)．
推薦文檔：SSL技術(shù)詳細(xì)說明
一直對(duì) SSL 的安全性比較模糊． 唉