||Cisco TelePresence Video Communication Server (VCS) Expressway X8.6 allows remote authenticated users to bypass intended read-only restrictions and upload Tandberg Linux Package (TLP) files by visiting an administrative page, aka Bug ID CSCuw55651.
|Base: ||4.0 (as of 14-12-2015 - 12:58)|
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 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.
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.
|NASL family||CISCO |
|NASL id||CISCO_TELEPRESENCE_VCS_MULTIPLE_880.NASL |
|description||According to its self-reported version, the Cisco TelePresence Video Communication Server (VCS) / Expressway running on the remote host is 8.x prior to 8.8. It is, therefore, affected by multiple vulnerabilities :
- A security feature bypass vulnerability exists, known as Bar Mitzvah, due to improper combination of state data with key data by the RC4 cipher algorithm during the initialization phase. A man-in-the-middle attacker can exploit this, via a brute-force attack using LSB values, to decrypt the traffic. (CVE-2015-2808)
- A flaw exists in the web framework of TelePresence Video Communication Server (VCS) Expressway due to missing authorization checks on certain administrative pages. An authenticated, remote attacker can exploit this to bypass read-only restrictions and install Tandberg Linux Packages (TLPs) without proper authorization.
- A flaw exists in certificate management and validation for the Mobile and Remote Access (MRA) component due to improper input validation of a trusted certificate. An unauthenticated, remote attacker can exploit this, using a trusted certificate, to bypass authentication and gain access to internal HTTP system resources.
- A heap buffer overflow condition exists in the EVP_EncodeUpdate() function within file crypto/evp/encode.c that is triggered when handling a large amount of input data. An unauthenticated, remote attacker can exploit this to cause a denial of service condition. (CVE-2016-2105)
- A heap buffer overflow condition exists in the EVP_EncryptUpdate() function within file crypto/evp/evp_enc.c that is triggered when handling a large amount of input data after a previous call occurs to the same function with a partial block. An unauthenticated, remote attacker can exploit this to cause a denial of service condition. (CVE-2016-2106)
- Multiple flaws exist in the aesni_cbc_hmac_sha1_cipher() function in file crypto/evp/e_aes_cbc_hmac_sha1.c and the aesni_cbc_hmac_sha256_cipher() function in file crypto/evp/e_aes_cbc_hmac_sha256.c that are triggered when the connection uses an AES-CBC cipher and AES-NI is supported by the server. A man-in-the-middle attacker can exploit these to conduct a padding oracle attack, resulting in the ability to decrypt the network traffic.
- A remote code execution vulnerability exists in the ASN.1 encoder due to an underflow condition that occurs when attempting to encode the value zero represented as a negative integer. An unauthenticated, remote attacker can exploit this to corrupt memory, resulting in the execution of arbitrary code. (CVE-2016-2108)
- Multiple unspecified flaws exist in the d2i BIO functions when reading ASN.1 data from a BIO due to invalid encoding causing a large allocation of memory.
An unauthenticated, remote attacker can exploit these to cause a denial of service condition through resource exhaustion. (CVE-2016-2109)
- An out-of-bounds read error exists in the X509_NAME_oneline() function within file crypto/x509/x509_obj.c when handling very long ASN.1 strings. An unauthenticated, remote attacker can exploit this to disclose the contents of stack memory.
- An information disclosure vulnerability exists in the file system permissions due to certain files having overly permissive permissions. An unauthenticated, local attacker can exploit this to disclose sensitive information. (Cisco bug ID CSCuw55636)
Note that Cisco bug ID CSCuw55636 and CVE-2015-6413 only affect versions 8.6.x prior to 8.8. |
|last seen||2019-02-21 |
|plugin id||92045 |
|title||Cisco TelePresence VCS / Expressway 8.x < 8.8 Multiple Vulnerabilities (Bar Mitzvah) |
|cisco||20151209 Cisco TelePresence Video Communication Server Expressway Web Framework Code Unauthorized Access Vulnerability |
|Last major update
||07-12-2016 - 13:20
||12-12-2015 - 22:59