第三方 Telegram 客戶端 -- Nekogram -- 被發現有後門,傳送使用者的電話號碼至某個外部的資料庫。

此外,如果使用者有多個 Profile,開發者會收到有關帳戶連結的資訊。

https://xcancel.com/sotanews/status/2039652946233688273

Sota News (@sotanews)

❗️ Unofficial Telegram Client Nekogram Transmits Account-Phone Number Links to Developer An IT expert who analyzed the Nekogram code informed SOTA about a backdoor discovered within the client: "The backdoor is hidden in the http://Extra.java file, which differs from the template uploaded to the repository. The obfuscated code sends data as an inline request to the @nekonotificationbot, leaving no trace. The same file implements account 'doxing' via several bots; it is possible that the leaked data is used to populate their databases." Additionally, the developer receives information regarding the linkage of accounts if a user has multiple profiles. The creator of the Nekogram client—presumably a Chinese national named Fan Li—was previously known for conducting DDoS attacks and unethical online behavior (including death threats against acquaintances). In early versions of the client, de-anonymization was applied only to Chinese phone numbers, which could have been used for political surveillance; however, it is now applied to all users. Notably, another unofficial Telegram client, "Telega," utilizes VK servers, providing the state with opportunities to monitor correspondence. Telegram itself has recently implemented an option to warn users if their interlocutor is using an unofficial client of the messenger. Illustration: Nekogram code fragment

Nitter

還是發一個完整一點的資訊好了。

這個漏洞之所以現在才被發現,是因為有人發現 GitHub 上開源的 repo 實際上和 release 版本不同,不同之處就是文件中提及的 `Extra.java` 這個檔案。

放在 GitHub 上公開的程式碼是「經過整理」的版本,而實際上發布的 app 是使用另一個包含後門的版本。

而這個後門幹的事情除了蒐集電話號碼,還有利用電話號碼,去確認與連結那些多個 profile 的使用者;所以哪個帳號是哪個人的?哪個是誰的小號?這個 Nekogram 的作者都知道。

https://thebadinteger.github.io/nekogram-phone-exfiltration/

Analysis of Nekogram 12.5.2 decompiled source - phone exfiltration backdoor discovered

Analysis of Nekogram 12.5.2 decompiled source - phone exfiltration backdoor discovered

nekogram-phone-exfiltration

然後是作者本人的回應也很直接,他完全承認蒐集了這些東西,而且附上了 Extra.java 。

(這個檔案中確實存在著蒐集電話號碼與使用者連結的程式碼,但依然是「經過整理的」,而不是用來建構的版本。仍無法確定實際發布的版本中,還有什麼未知的行為。)

在這個回應中的 spolier 中的文字表示,他雖然蒐集了這些資訊,但是沒有分享出去,信或不信就看各人了。