ID CVE-2017-9079
Summary Dropbear before 2017.75 might allow local users to read certain files as root, if the file has the authorized_keys file format with a command= option. This occurs because ~/.ssh/authorized_keys is read with root privileges and symlinks are followed.
References
Vulnerable Configurations
  • cpe:2.3:a:dropbear_ssh_project:dropbear_ssh:2016.74
    cpe:2.3:a:dropbear_ssh_project:dropbear_ssh:2016.74
CVSS
Base: 4.7
Impact:
Exploitability:
CWE CWE-264
CAPEC
  • Accessing, Modifying or Executing Executable Files
    An attack of this type exploits a system's configuration that allows an attacker to either directly access an executable file, for example through shell access; or in a possible worst case allows an attacker to upload a file and then execute it. Web servers, ftp servers, and message oriented middleware systems which have many integration points are particularly vulnerable, because both the programmers and the administrators must be in synch regarding the interfaces and the correct privileges for each interface.
  • Leverage Executable Code in Non-Executable Files
    An attack of this type exploits a system's trust in configuration and resource files, when the executable loads the resource (such as an image file or configuration file) the attacker has modified the file to either execute malicious code directly or manipulate the target process (e.g. application server) to execute based on the malicious configuration parameters. Since systems are increasingly interrelated mashing up resources from local and remote sources the possibility of this attack occurring is high. The attack can be directed at a client system, such as causing buffer overrun through loading seemingly benign image files, as in Microsoft Security Bulletin MS04-028 where specially crafted JPEG files could cause a buffer overrun once loaded into the browser. Another example targets clients reading pdf files. In this case the attacker simply appends javascript to the end of a legitimate url for a pdf (http://www.gnucitizen.org/blog/danger-danger-danger/) http://path/to/pdf/file.pdf#whatever_name_you_want=javascript:your_code_here The client assumes that they are reading a pdf, but the attacker has modified the resource and loaded executable javascript into the client's browser process. The attack can also target server processes. The attacker edits the resource or configuration file, for example a web.xml file used to configure security permissions for a J2EE app server, adding role name "public" grants all users with the public role the ability to use the administration functionality. The server trusts its configuration file to be correct, but when they are manipulated, the attacker gains full control.
  • Blue Boxing
    This type of attack against older telephone switches and trunks has been around for decades. A tone is sent by an adversary to impersonate a supervisor signal which has the effect of rerouting or usurping command of the line. While the US infrastructure proper may not contain widespread vulnerabilities to this type of attack, many companies are connected globally through call centers and business process outsourcing. These international systems may be operated in countries which have not upgraded Telco infrastructure and so are vulnerable to Blue boxing. Blue boxing is a result of failure on the part of the system to enforce strong authorization for administrative functions. While the infrastructure is different than standard current applications like web applications, there are historical lessons to be learned to upgrade the access control for administrative functions.
  • Restful Privilege Elevation
    Rest uses standard HTTP (Get, Put, Delete) style permissions methods, but these are not necessarily correlated generally with back end programs. Strict interpretation of HTTP get methods means that these HTTP Get services should not be used to delete information on the server, but there is no access control mechanism to back up this logic. This means that unless the services are properly ACL'd and the application's service implementation are following these guidelines then an HTTP request can easily execute a delete or update on the server side. The attacker identifies a HTTP Get URL such as http://victimsite/updateOrder, which calls out to a program to update orders on a database or other resource. The URL is not idempotent so the request can be submitted multiple times by the attacker, additionally, the attacker may be able to exploit the URL published as a Get method that actually performs updates (instead of merely retrieving data). This may result in malicious or inadvertent altering of data on the server.
  • Target Programs with Elevated Privileges
    This attack targets programs running with elevated privileges. The attacker would try to leverage a bug in the running program and get arbitrary code to execute with elevated privileges. For instance an attacker would look for programs that write to the system directories or registry keys (such as HKLM, which stores a number of critical Windows environment variables). These programs are typically running with elevated privileges and have usually not been designed with security in mind. Such programs are excellent exploit targets because they yield lots of power when they break. The malicious user try to execute its code at the same level as a privileged system call.
  • Manipulating Input to File System Calls
    An attacker manipulates inputs to the target software which the target software passes to file system calls in the OS. The goal is to gain access to, and perhaps modify, areas of the file system that the target software did not intend to be accessible.
nessus via4
  • NASL family Fedora Local Security Checks
    NASL id FEDORA_2017-A50319C820.NASL
    description Security fixes for CVE-2017-9078 CVE-2017-9079 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen 2017-10-29
    modified 2017-07-17
    plugin id 101694
    published 2017-07-17
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=101694
    title Fedora 26 : dropbear (2017-a50319c820)
  • NASL family Fedora Local Security Checks
    NASL id FEDORA_2017-8E9BD58CBB.NASL
    description Security fixes for CVE-2017-9078 CVE-2017-9079 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen 2017-10-29
    modified 2017-06-05
    plugin id 100607
    published 2017-06-05
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=100607
    title Fedora 25 : dropbear (2017-8e9bd58cbb)
  • NASL family FreeBSD Local Security Checks
    NASL id FREEBSD_PKG_60931F9855A711E78514589CFC0654E1.NASL
    description Matt Johnston reports : Fix double-free in server TCP listener cleanup A double-free in the server could be triggered by an authenticated user if dropbear is running with -a (Allow connections to forwarded ports from any host) This could potentially allow arbitrary code execution as root by an authenticated user. Fix information disclosure with ~/.ssh/authorized_keys symlink. Dropbear parsed authorized_keys as root, even if it were a symlink. The fix is to switch to user permissions when opening authorized_keys.
    last seen 2017-10-29
    modified 2017-07-05
    plugin id 101217
    published 2017-07-05
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=101217
    title FreeBSD : Dropbear -- two vulnerabilities (60931f98-55a7-11e7-8514-589cfc0654e1)
  • NASL family Fedora Local Security Checks
    NASL id FEDORA_2017-B22DE5C767.NASL
    description Security fixes for CVE-2017-9078 CVE-2017-9079 Note that Tenable Network Security has extracted the preceding description block directly from the Fedora update system website. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen 2017-10-29
    modified 2017-06-05
    plugin id 100608
    published 2017-06-05
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=100608
    title Fedora 24 : dropbear (2017-b22de5c767)
  • NASL family Debian Local Security Checks
    NASL id DEBIAN_DLA-948.NASL
    description A vulnerability was found in Dropbear, a lightweight SSH2 server and client. CVE-2017-9079 Jann Horn discovered a local information leak in parsing the .authorized_keys file. For Debian 7 'Wheezy', this problem has been fixed in version 2012.55-1.3+deb7u2. We recommend that you upgrade your dropbear packages. NOTE: Tenable Network Security has extracted the preceding description block directly from the DLA security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.
    last seen 2017-10-29
    modified 2017-08-14
    plugin id 100304
    published 2017-05-22
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=100304
    title Debian DLA-948-1 : dropbear security update
  • NASL family Debian Local Security Checks
    NASL id DEBIAN_DSA-3859.NASL
    description Two vulnerabilities were found in Dropbear, a lightweight SSH2 server and client : - CVE-2017-9078 Mark Shepard discovered a double free in the TCP listener cleanup which could result in denial of service by an authenticated user if Dropbear is running with the '-a' option. - CVE-2017-9079 Jann Horn discovered a local information leak in parsing the .authorized_keys file.
    last seen 2017-10-29
    modified 2017-08-14
    plugin id 100306
    published 2017-05-22
    reporter Tenable
    source https://www.tenable.com/plugins/index.php?view=single&id=100306
    title Debian DSA-3859-1 : dropbear - security update
refmap via4
confirm http://lists.ucc.gu.uwa.edu.au/pipermail/dropbear/2017q2/001985.html
debian DSA-3859
Last major update 19-05-2017 - 10:29
Published 19-05-2017 - 10:29
Last modified 03-11-2017 - 21:29
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