Vulnerabilities > CVE-2019-9896 - Uncontrolled Search Path Element vulnerability in multiple products
Attack vector
LOCAL Attack complexity
LOW Privileges required
NONE Confidentiality impact
PARTIAL Integrity impact
PARTIAL Availability impact
PARTIAL Summary
In PuTTY versions before 0.71 on Windows, local attackers could hijack the application by putting a malicious help file in the same directory as the executable.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| Application | Putty
| 28 |
| Application | 1 | |
| OS | 1 | |
| OS | 1 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Leveraging/Manipulating Configuration File Search Paths This attack loads a malicious resource into a program's standard path used to bootstrap and/or provide contextual information for a program like a path variable or classpath. J2EE applications and other component based applications that are built from multiple binaries can have very long list of dependencies to execute. If one of these libraries and/or references is controllable by the attacker then application controls can be circumvented by the attacker. A standard UNIX path looks similar to this If the attacker modifies the path variable to point to a locale that includes malicious resources then the user unwittingly can execute commands on the attackers' behalf: This is a form of usurping control of the program and the attack can be done on the classpath, database resources, or any other resources built from compound parts. At runtime detection and blocking of this attack is nearly impossible, because the configuration allows execution.
- DLL Search Order Hijacking The attacker exploits the functionality of the Windows DLL loader where the process loading the DLL searches for the DLL to be loaded first in the same directory in which the process binary resides and then in other directories (e.g., System32). Exploitation of this preferential search order can allow an attacker to make the loading process load the attackers' rogue DLL rather than the legitimate DLL. For instance, an attacker with access to the file system may place a malicious ntshrui.dll in the C:\Windows directory. This DLL normally resides in the System32 folder. Process explorer.exe which also resides in C:\Windows, upon trying to load the ntshrui.dll from the System32 folder will actually load the DLL supplied by the attacker simply because of the preferential search order. Since the attacker has placed its malicious ntshrui.dll in the same directory as the loading explorer.exe process, the DLL supplied by the attacker will be found first and thus loaded in lieu of the legitimate DLL. Since explorer.exe is loaded during the boot cycle, the attackers' malware is guaranteed to execute. This attack can be leveraged with many different DLLs and with many different loading processes. No forensic trails are left in the system's registry or file system that an incorrect DLL had been loaded.
Nessus
NASL family SuSE Local Security Checks NASL id OPENSUSE-2019-1113.NASL description This update for putty fixes the following issues : Update to new upstream release 0.71 [boo#1129633] - CVE-2019-9894: Fixed a remotely triggerable memory overwrite in RSA key exchange, which can occur before host key verification potential recycling of random numbers used in cryptography. - CVE-2019-9895: Fixed a remotely triggerable buffer overflow in any kind of server-to-client forwarding. - CVE-2019-9897: Fixed multiple denial-of-service attacks that can be triggered by writing to the terminal. - CVE-2019-9898: Fixed potential recycling of random numbers used in cryptography - CVE-2019-9896 (Windows only): Fixed hijacking by a malicious help file in the same directory as the executable - Major rewrite of the crypto code to remove cache and timing side channels. last seen 2020-06-01 modified 2020-06-02 plugin id 123660 published 2019-04-03 reporter This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/123660 title openSUSE Security Update : putty (openSUSE-2019-1113) code # # (C) Tenable Network Security, Inc. # # The descriptive text and package checks in this plugin were # extracted from openSUSE Security Update openSUSE-2019-1113. # # The text description of this plugin is (C) SUSE LLC. # include("compat.inc"); if (description) { script_id(123660); script_version("1.2"); script_cvs_date("Date: 2020/01/27"); script_cve_id("CVE-2019-9894", "CVE-2019-9895", "CVE-2019-9896", "CVE-2019-9897", "CVE-2019-9898"); script_name(english:"openSUSE Security Update : putty (openSUSE-2019-1113)"); script_summary(english:"Check for the openSUSE-2019-1113 patch"); script_set_attribute( attribute:"synopsis", value:"The remote openSUSE host is missing a security update." ); script_set_attribute( attribute:"description", value: "This update for putty fixes the following issues : Update to new upstream release 0.71 [boo#1129633] - CVE-2019-9894: Fixed a remotely triggerable memory overwrite in RSA key exchange, which can occur before host key verification potential recycling of random numbers used in cryptography. - CVE-2019-9895: Fixed a remotely triggerable buffer overflow in any kind of server-to-client forwarding. - CVE-2019-9897: Fixed multiple denial-of-service attacks that can be triggered by writing to the terminal. - CVE-2019-9898: Fixed potential recycling of random numbers used in cryptography - CVE-2019-9896 (Windows only): Fixed hijacking by a malicious help file in the same directory as the executable - Major rewrite of the crypto code to remove cache and timing side channels." ); script_set_attribute( attribute:"see_also", value:"https://bugzilla.opensuse.org/show_bug.cgi?id=1129633" ); script_set_attribute( attribute:"solution", value:"Update the affected putty packages." ); script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P"); script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C"); script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"); script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C"); script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:putty"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:putty-debuginfo"); script_set_attribute(attribute:"cpe", value:"p-cpe:/a:novell:opensuse:putty-debugsource"); script_set_attribute(attribute:"cpe", value:"cpe:/o:novell:opensuse:15.0"); script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/21"); script_set_attribute(attribute:"patch_publication_date", value:"2019/04/02"); script_set_attribute(attribute:"plugin_publication_date", value:"2019/04/03"); script_set_attribute(attribute:"generated_plugin", value:"current"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_copyright(english:"This script is Copyright (C) 2019-2020 and is owned by Tenable, Inc. or an Affiliate thereof."); script_family(english:"SuSE Local Security Checks"); script_dependencies("ssh_get_info.nasl"); script_require_keys("Host/local_checks_enabled", "Host/SuSE/release", "Host/SuSE/rpm-list", "Host/cpu"); exit(0); } include("audit.inc"); include("global_settings.inc"); include("rpm.inc"); if (!get_kb_item("Host/local_checks_enabled")) audit(AUDIT_LOCAL_CHECKS_NOT_ENABLED); release = get_kb_item("Host/SuSE/release"); if (isnull(release) || release =~ "^(SLED|SLES)") audit(AUDIT_OS_NOT, "openSUSE"); if (release !~ "^(SUSE15\.0)$") audit(AUDIT_OS_RELEASE_NOT, "openSUSE", "15.0", release); if (!get_kb_item("Host/SuSE/rpm-list")) audit(AUDIT_PACKAGE_LIST_MISSING); ourarch = get_kb_item("Host/cpu"); if (!ourarch) audit(AUDIT_UNKNOWN_ARCH); if (ourarch !~ "^(x86_64)$") audit(AUDIT_ARCH_NOT, "x86_64", ourarch); flag = 0; if ( rpm_check(release:"SUSE15.0", reference:"putty-0.71-lp150.9.1") ) flag++; if ( rpm_check(release:"SUSE15.0", reference:"putty-debuginfo-0.71-lp150.9.1") ) flag++; if ( rpm_check(release:"SUSE15.0", reference:"putty-debugsource-0.71-lp150.9.1") ) flag++; if (flag) { if (report_verbosity > 0) security_hole(port:0, extra:rpm_report_get()); else security_hole(0); exit(0); } else { tested = pkg_tests_get(); if (tested) audit(AUDIT_PACKAGE_NOT_AFFECTED, tested); else audit(AUDIT_PACKAGE_NOT_INSTALLED, "putty / putty-debuginfo / putty-debugsource"); }NASL family Windows NASL id PUTTY_071.NASL description The remote host has a version of PuTTY installed that is prior to 0.71. It is, therefore, affected by multiple vulnerabilities including: - A remotely triggerable buffer overflow in any kind of server-to-client forwarding. (CVE-2019-9895) - Potential recycling of random numbers used in cryptography. (CVE-2019-9898) - A remotely triggerable memory overwrite in RSA key exchange can occur before host key verification. (CVE-2019-9894) last seen 2020-06-01 modified 2020-06-02 plugin id 123418 published 2019-03-27 reporter This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/123418 title PuTTY < 0.71 Multiple Vulnerabilities code # # (C) Tenable Network Security, Inc. # include("compat.inc"); if (description) { script_id(123418); script_version("1.2"); script_cvs_date("Date: 2019/10/30 13:24:47"); script_cve_id( "CVE-2019-9894", "CVE-2019-9895", "CVE-2019-9896", "CVE-2019-9897", "CVE-2019-9898" ); script_bugtraq_id( 107484, 107523 ); script_name(english:"PuTTY < 0.71 Multiple Vulnerabilities"); script_summary(english:"Checks the version of PuTTY."); script_set_attribute(attribute:"synopsis", value: "The remote Windows host has an SSH client that is affected by multiple vulnerabilities."); script_set_attribute(attribute:"description", value: "The remote host has a version of PuTTY installed that is prior to 0.71. It is, therefore, affected by multiple vulnerabilities including: - A remotely triggerable buffer overflow in any kind of server-to-client forwarding. (CVE-2019-9895) - Potential recycling of random numbers used in cryptography. (CVE-2019-9898) - A remotely triggerable memory overwrite in RSA key exchange can occur before host key verification. (CVE-2019-9894)"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-auth-prompt-spoofing.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?fc188a9c"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-chm-hijack.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?cd82820f"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-fd-set-overflow.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?e116cf63"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-rng-reuse.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?39988fba"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-rsa-kex-integer-overflow.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?50d03d73"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-terminal-dos-combining-chars.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?dc4b5e69"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-terminal-dos-combining-chars-double-width-gtk.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?d52aebfd"); # https://www.chiark.greenend.org.uk/~sgtatham/putty/wishlist/vuln-terminal-dos-one-column-cjk.html script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?819250a8"); script_set_attribute(attribute:"see_also", value:"http://www.chiark.greenend.org.uk/~sgtatham/putty/changes.html"); script_set_attribute(attribute:"solution", value:"Upgrade to PuTTY version 0.71 or later."); script_set_cvss_base_vector("CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P"); script_set_cvss_temporal_vector("CVSS2#E:U/RL:OF/RC:C"); script_set_cvss3_base_vector("CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"); script_set_cvss3_temporal_vector("CVSS:3.0/E:U/RL:O/RC:C"); script_set_attribute(attribute:"cvss_score_source", value:"CVE-2019-9895"); script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available"); script_set_attribute(attribute:"vuln_publication_date", value:"2019/03/16"); script_set_attribute(attribute:"patch_publication_date", value:"2019/03/16"); script_set_attribute(attribute:"plugin_publication_date", value:"2019/03/27"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"cpe:/a:simon_tatham:putty"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_family(english:"Windows"); script_copyright(english:"This script is Copyright (C) 2019 and is owned by Tenable, Inc. or an Affiliate thereof."); script_dependencies("putty_installed.nasl"); script_require_keys("installed_sw/PuTTY", "SMB/Registry/Enumerated"); exit(0); } include("vcf.inc"); get_kb_item_or_exit("SMB/Registry/Enumerated"); app_info = vcf::get_app_info(app:"PuTTY", win_local:TRUE); constraints = [ { "fixed_version" : "0.71" } ]; vcf::check_version_and_report(app_info:app_info, constraints:constraints, severity:SECURITY_HOLE);