CVE-2015-6305 : Detail

CVE-2015-6305

A08-Soft and Data Integrity Fail
5.66%V4
Local
2015-09-24
23h00 +00:00
2016-12-06
17h57 +00:00
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CVE Descriptions

Untrusted search path vulnerability in the CMainThread::launchDownloader function in vpndownloader.exe in Cisco AnyConnect Secure Mobility Client 2.0 through 4.1 on Windows allows local users to gain privileges via a Trojan horse DLL in the current working directory, as demonstrated by dbghelp.dll, aka Bug ID CSCuv01279. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-4211.

CVE Informations

Related Weaknesses

CWE-ID Weakness Name Source
CWE-426 Untrusted Search Path
The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control.

Metrics

Metrics Score Severity CVSS Vector Source
V2 7.2 AV:L/AC:L/Au:N/C:C/I:C/A:C nvd@nist.gov

EPSS

EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.

EPSS Score

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

EPSS Percentile

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
EPSS First.org

Exploit information

Exploit Database EDB-ID : 38289

Publication date : 2015-09-21 22h00 +00:00
Author : Google Security Research
EDB Verified : Yes

Source: https://code.google.com/p/google-security-research/issues/detail?id=460 Cisco AnyConnect Secure Mobility Client v3.1.08009 Elevation of Privilege Platform: Windows 8.1 Update, Client version 3.1.08009 (tested on 32 bit only) Class: Elevation of Privilege Summary: The fix for CVE-2015-4211 is insufficient which allows a local application to elevate to local system through the CMainThread::launchDownloader command. Description: This is directly related to http://tools.cisco.com/security/center/viewAlert.x?alertId=39466. The fix for this issue seemed to be modifying the file verification process to only allow a signed file which also has in its version information the original filename of vpndownloader.exe. This, along with the name change makes it clear you only want to execute the VPN Downloader application. However the code doesn’t limit the location of the executable file, so one exploitation vector is DLL planting. The downloader loads a lot of DLLs from the executable directory first, so by copying the vpndownloader.exe file from Program Files to a temporary directory and dropping an appropriately named DLL you can get code execution as SYSTEM. One such DLL is dbghelp.dll which is loaded explicitly by the downloader using LoadLibrary, but there are many more. Even if by luck the executable wasn’t vulnerable to DLL planting there’s many other potential issues, for example even though a lock is made on the executable file during signature verification it’s possible to use symbolic links to exploit this as a race condition and switch the executable file after verification has completed. There’s many other possibilities as well. I’d recommend that if you’re really only supposed to be executing vpndownloader you only execute it from the secure program files directory which would eliminate this issue. This was based on work previous done by Kostya Kortchinsky. Proof of Concept: The PoC demonstrates the vulnerability and should create a copy of CMD.EXE running at SYSTEM on the current user’s desktop. I’ve provided source for the exploit.exe written in C# 4 and the dbghelp.dll in C++, as well as binaries. It should run on 32 and 64 bit platforms but I’ve only tested it on 32 bit. 1) Copy the exploit.exe and dbghelp.dll to a location on a local hard disk which the current user can write to. 2) Execute exploit.exe as the normal user 3) A command prompt should appear running at SYSTEM Expected Result: The service rejects the executable request Observed Result: The service executes the file from the temporary directory and allows for elevation. Proof of Concept: https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/38289.zip

Products Mentioned

Configuraton 0

Cisco>>Anyconnect_secure_mobility_client >> Version 2.0.0343

    Cisco>>Anyconnect_secure_mobility_client >> Version 2.1.0.148

      Cisco>>Anyconnect_secure_mobility_client >> Version 2.2.0133

        Cisco>>Anyconnect_secure_mobility_client >> Version 2.2.0136

          Cisco>>Anyconnect_secure_mobility_client >> Version 2.2.0140

            Cisco>>Anyconnect_secure_mobility_client >> Version 2.3.0185

              Cisco>>Anyconnect_secure_mobility_client >> Version 2.3.0254

                Cisco>>Anyconnect_secure_mobility_client >> Version 2.3.1003

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.3.2016

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.4.0202

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.4.1012

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.0217

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.2006

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.2010

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.2011

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.2014

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.2017

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.2018

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.2019

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.3041

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.3046

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.3051

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.3054

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5.3055

                  Cisco>>Anyconnect_secure_mobility_client >> Version 2.5_base

                    Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.0

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.0629

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.1047

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.2052

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.3050

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.3054

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.4235

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.5075

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.5080

                      Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.09231

                        Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.09266

                          Cisco>>Anyconnect_secure_mobility_client >> Version 3.0.09353

                            Cisco>>Anyconnect_secure_mobility_client >> Version 3.1\(60\)

                            Cisco>>Anyconnect_secure_mobility_client >> Version 3.1.0

                            Cisco>>Anyconnect_secure_mobility_client >> Version 3.1.02043

                              Cisco>>Anyconnect_secure_mobility_client >> Version 3.1.05182

                                Cisco>>Anyconnect_secure_mobility_client >> Version 3.1.05187

                                  Cisco>>Anyconnect_secure_mobility_client >> Version 3.1.06073

                                    Cisco>>Anyconnect_secure_mobility_client >> Version 3.1.07021

                                      Cisco>>Anyconnect_secure_mobility_client >> Version 4.0\(48\)

                                        Cisco>>Anyconnect_secure_mobility_client >> Version 4.0\(64\)

                                          Cisco>>Anyconnect_secure_mobility_client >> Version 4.0\(2049\)

                                          Cisco>>Anyconnect_secure_mobility_client >> Version 4.0.0

                                            Cisco>>Anyconnect_secure_mobility_client >> Version 4.0.00048

                                              Cisco>>Anyconnect_secure_mobility_client >> Version 4.0.00051

                                                Cisco>>Anyconnect_secure_mobility_client >> Version 4.1.0

                                                  Microsoft>>Windows >> Version *

                                                  References

                                                  http://www.securitytracker.com/id/1033643
                                                  Tags : vdb-entry, x_refsource_SECTRACK
                                                  https://www.exploit-db.com/exploits/38289/
                                                  Tags : exploit, x_refsource_EXPLOIT-DB
                                                  http://seclists.org/fulldisclosure/2015/Sep/80
                                                  Tags : mailing-list, x_refsource_FULLDISC
                                                  The information presented on CVE Find originates from several carefully selected reference sources. CVE data is provided by MITRE Corporation and the National Vulnerability Database (NVD). The Known Exploited Vulnerabilities (KEV) catalog is sourced from the Cybersecurity and Infrastructure Security Agency (CISA), while EPSS scores come from FIRST.org. Additionally, data regarding software weaknesses (CWE) and common attack patterns (CAPEC) is maintained by MITRE Corporation, and information on hardware and software configurations (CPE) is provided by the NVD.