Dropbear SSH Server Username Format String Vulnerability

BID:8439

Info

Dropbear SSH Server Username Format String Vulnerability

Bugtraq ID: 8439
Class: Design Error
CVE:
Remote: Yes
Local: No
Published: Aug 18 2003 12:00AM
Updated: Aug 18 2003 12:00AM
Credit: The discovery of this vulnerability has been credit to Joel Eriksson of 0xbadc0ded.
Vulnerable: Dropbear SSH Server 0.34
Dropbear SSH Server 0.33
Dropbear SSH Server 0.32
Dropbear SSH Server 0.31
Dropbear SSH Server 0.30
Dropbear SSH Server 0.29
Dropbear SSH Server 0.28
Not Vulnerable: Dropbear SSH Server 0.35

Discussion

Dropbear SSH Server Username Format String Vulnerability

A remote vulnerability has been discovered in Dropbear SSH Server that could allow an attacker to execute arbitrary code on a target system. The issue lies in a format string error while calling the syslog() function during the authentication stage.

As a result of this bug, an attacker may be capable of passing specifically calculated format specifiers embedded within the supplied username. When this value is later stored in a buffer and passed to an incorrectly formatted call to the syslog() function, the attacker-supplied format specifiers be interpreted and thus influence the flow of execution within the program; ultimately resulting in the execution of arbitrary code.

This vulnerability affects Dropbear SSH Server v0.34 and earlier.

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