Format string error in Dropbear SSH server

1) Format string error

EUVDB-ID: #VU309

Risk: Low

CVSSv3.1: 6.8 [CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: N/A

CWE-ID: CWE-134 - Use of Externally-Controlled Format String

Exploit availability: No

Description

The vulnerability allows a remote authenticated attacker to execute arbitrary code on the target system.

The vulnerability exists due to a format string error when handling usernames, containing format string characters (e.g. %) in getpwnam() function. A remote attacker with the ability to manipulate his username can execute arbitrary code on the target system.

Successful exploitation may allow an attacker to gain complete control over the vulnerable system.

Mitigation

Update to the latest version 2016.74.

Vulnerable software versions

Dropbear: 2013.56 - 2016.73

External links

http://matt.ucc.asn.au/dropbear/CHANGES

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

The attacker would have to login to the system and perform certain actions in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.