Amazon Linux AMI : curl (ALAS-2017-919)

Medium Nessus Plugin ID 104393


The remote Amazon Linux AMI host is missing a security update.


FTP PWD response parser out of bounds read

libcurl may read outside of a heap allocated buffer when doing FTP.
When libcurl connects to an FTP server and successfully logs in (anonymous or not), it asks the server for the current directory with the `PWD` command. The server then responds with a 257 response containing the path, inside double quotes. The returned path name is then kept by libcurl for subsequent uses. Due to a flaw in the string parser for this directory name, a directory name passed like this but without a closing double quote would lead to libcurl not adding a trailing NUL byte to the buffer holding the name. When libcurl would then later access the string, it could read beyond the allocated heap buffer and crash or wrongly access data beyond the buffer, thinking it was part of the path. A malicious server could abuse this fact and effectively prevent libcurl-based clients to work with it - the PWD command is always issued on new FTP connections and the mistake has a high chance of causing a segfault. The simple fact that this has issue remained undiscovered for this long could suggest that malformed PWD responses are rare in benign servers. We are not aware of any exploit of this flaw. This bug was introduced in commit [415d2e7cb7](, March 2005. In libcurl version 7.56.0, the parser always zero terminates the string but also rejects it if not terminated properly with a final double quote. (CVE-2017-1000254 )


Run 'yum update curl' to update your system.

See Also

Plugin Details

Severity: Medium

ID: 104393

File Name: ala_ALAS-2017-919.nasl

Version: $Revision: 3.2 $

Type: local

Agent: unix

Published: 2017/11/06

Modified: 2018/01/25

Dependencies: 12634

Risk Information

Risk Factor: Medium


Base Score: 5

Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:N/A:P


Base Score: 7.5

Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:curl, p-cpe:/a:amazon:linux:curl-debuginfo, p-cpe:/a:amazon:linux:libcurl, p-cpe:/a:amazon:linux:libcurl-devel, cpe:/o:amazon:linux

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Patch Publication Date: 2017/11/02

Reference Information

CVE: CVE-2017-1000254

ALAS: 2017-919