Title: QwikMail HELO Command Buffer Overflow Vulnerability
Severity: HIGH
Description:
QwikMail (qwik-smtpd) is an open source Mail Transfer Agent (MTA) designed for UNIX/Linux variants.
QwikMail is reportedly prone to a remotely exploitable buffer overflow vulnerability. The issue is due to insufficient bounds checking of client-supplied SMTP HELO request data.
This issue could theoretically be exploited to execute arbitrary code. The source of the vulnerability is that the client HELO request is copied into a 32 byte clientHelo buffer using the strcpy() function. This operation is performed without placing an adequate limit on the size of the source data.
Due to the memory layout, it is also reportedly possible to overwrite an adjacent buffer in a manner that will allow a remote attacker to abuse the server as an unauthorized mail relay. Specifically, the buffer for the localIP variable is stored adjacent to the 32 byte clientHelo buffer. If overwritten with a value of "127.0.0.1", the server will relay the incoming message. This could be abused to send spam or other malicious emails anonymously.
Affected Products:
- Amir Malik QwikMail 0.3.0
References:
- "D. J. Bernstein" <djb@cr.yp.to>: [remote] [exhaust] qwik-smtpd overflows clientHelo buffer
- Amir Malik: QwikMail Home Page
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