Buffer overflow in TCP syslog server (receiver) components in rsyslog

Rsyslog is a rocket-fast system for log processing. Modules for TCP syslog reception have a potential heap buffer overflow when octet-counted framing is used. This can result in a segfault or some other malfunction. As of our understanding, this vulnerability can not be used for remote code execution. But there may still be a slight chance for experts to do that. The bug occurs when the octet count is read. While there is a check for the maximum number of octets, digits are written to a heap buffer even when the octet count is over the maximum, This can be used to overrun the memory buffer. However, once the sequence of digits stop, no additional characters can be added to the buffer. In our opinion, this makes remote exploits impossible or at least highly complex. Octet-counted framing is one of two potential framing modes. It is relatively uncommon, but enabled by default on receivers. Modules `imtcp`, `imptcp`, `imgssapi`, and `imhttp` are used for regular syslog message reception. It is best practice not to directly expose them to the public. When this practice is followed, the risk is considerably lower. Module `imdiag` is a diagnostics module primarily intended for testbench runs. We do not expect it to be present on any production installation. Octet-counted framing is not very common. Usually, it needs to be specifically enabled at senders. If users do not need it, they can turn it off for the most important modules. This will mitigate the vulnerability.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

未进行输入大小检查的缓冲区拷贝(传统缓冲区溢出)

Adiscon Rsyslog 安全漏洞

Adiscon Rsyslog是德国Adiscon公司的一个用于收集系统日志的库。 Adiscon Rsyslog 8.2204.0版本及之前版本存在安全漏洞，该漏洞源于使用八位字节计数的帧时，用于接收 TCP 系统日志的模块会出现堆缓冲区溢出，攻击者利用该漏洞可以破坏堆值，导致数据完整性和可用性。

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