Vulnerabilities > CVE-2020-3235 - Improper Input Validation vulnerability in multiple products
Attack vector
NETWORK Attack complexity
MEDIUM Privileges required
SINGLE Confidentiality impact
NONE Integrity impact
NONE Availability impact
COMPLETE Summary
A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS Software and Cisco IOS XE Software on Catalyst 4500 Series Switches could allow an authenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to insufficient input validation when the software processes specific SNMP object identifiers. An attacker could exploit this vulnerability by sending a crafted SNMP packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Note: To exploit this vulnerability by using SNMPv2c or earlier, the attacker must know the SNMP read-only community string for an affected system. To exploit this vulnerability by using SNMPv3, the attacker must know the user credentials for the affected system.
Vulnerable Configurations
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Buffer Overflow via Environment Variables This attack pattern involves causing a buffer overflow through manipulation of environment variables. Once the attacker finds that they can modify an environment variable, they may try to overflow associated buffers. This attack leverages implicit trust often placed in environment variables.
- Server Side Include (SSI) Injection An attacker can use Server Side Include (SSI) Injection to send code to a web application that then gets executed by the web server. Doing so enables the attacker to achieve similar results to Cross Site Scripting, viz., arbitrary code execution and information disclosure, albeit on a more limited scale, since the SSI directives are nowhere near as powerful as a full-fledged scripting language. Nonetheless, the attacker can conveniently gain access to sensitive files, such as password files, and execute shell commands.
- Cross Zone Scripting An attacker is able to cause a victim to load content into their web-browser that bypasses security zone controls and gain access to increased privileges to execute scripting code or other web objects such as unsigned ActiveX controls or applets. This is a privilege elevation attack targeted at zone-based web-browser security. In a zone-based model, pages belong to one of a set of zones corresponding to the level of privilege assigned to that page. Pages in an untrusted zone would have a lesser level of access to the system and/or be restricted in the types of executable content it was allowed to invoke. In a cross-zone scripting attack, a page that should be assigned to a less privileged zone is granted the privileges of a more trusted zone. This can be accomplished by exploiting bugs in the browser, exploiting incorrect configuration in the zone controls, through a cross-site scripting attack that causes the attackers' content to be treated as coming from a more trusted page, or by leveraging some piece of system functionality that is accessible from both the trusted and less trusted zone. This attack differs from "Restful Privilege Escalation" in that the latter correlates to the inadequate securing of RESTful access methods (such as HTTP DELETE) on the server, while cross-zone scripting attacks the concept of security zones as implemented by a browser.
- Cross Site Scripting through Log Files An attacker may leverage a system weakness where logs are susceptible to log injection to insert scripts into the system's logs. If these logs are later viewed by an administrator through a thin administrative interface and the log data is not properly HTML encoded before being written to the page, the attackers' scripts stored in the log will be executed in the administrative interface with potentially serious consequences. This attack pattern is really a combination of two other attack patterns: log injection and stored cross site scripting.
- Command Line Execution through SQL Injection An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.
Nessus
NASL family CISCO NASL id CISCO-SA-SNMP-DOS-USXSYTK5-IOS.NASL description According to its self-reported version, IOS is affected by a vulnerability in the Simple Network Management Protocol (SNMP) subsystem due to insufficient input validation when the software processes specific SNMP object identifiers. An authenticated, remote attacker can exploit this, by sending a crafted SNMP packet to an affected device, in order to cause a denial of service (DoS) condition. Please see the included Cisco BIDs and Cisco Security Advisory for more information. last seen 2020-06-12 modified 2020-06-05 plugin id 137144 published 2020-06-05 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/137144 title Cisco IOS Software Simple Network Management Protocol DoS (cisco-sa-snmp-dos-USxSyTk5) code #TRUSTED 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 # # (C) Tenable Network Security, Inc. # include('compat.inc'); if (description) { script_id(137144); script_version("1.6"); script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/10"); script_cve_id("CVE-2020-3235"); script_xref(name:"CISCO-BUG-ID", value:"CSCvk71355"); script_xref(name:"CISCO-SA", value:"cisco-sa-snmp-dos-USxSyTk5"); script_xref(name:"IAVA", value:"2020-A-0239"); script_name(english:"Cisco IOS Software Simple Network Management Protocol DoS (cisco-sa-snmp-dos-USxSyTk5)"); script_set_attribute(attribute:"synopsis", value: "The remote device is missing a vendor-supplied security patch"); script_set_attribute(attribute:"description", value: "According to its self-reported version, IOS is affected by a vulnerability in the Simple Network Management Protocol (SNMP) subsystem due to insufficient input validation when the software processes specific SNMP object identifiers. An authenticated, remote attacker can exploit this, by sending a crafted SNMP packet to an affected device, in order to cause a denial of service (DoS) condition. Please see the included Cisco BIDs and Cisco Security Advisory for more information."); # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snmp-dos-USxSyTk5 script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?528a5571"); script_set_attribute(attribute:"see_also", value:"http://tools.cisco.com/security/center/viewErp.x?alertId=ERP-73388"); script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvk71355"); script_set_attribute(attribute:"solution", value: "Upgrade to the relevant fixed version referenced in Cisco bug ID CSCvk71355 or apply the workaround mentioned in the vendor advisory"); script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:S/C:N/I:N/A:C"); 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:L/UI:N/S:C/C:N/I:N/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-2020-3235"); script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available"); script_cwe_id(118); script_set_attribute(attribute:"vuln_publication_date", value:"2020/06/03"); script_set_attribute(attribute:"patch_publication_date", value:"2020/06/03"); script_set_attribute(attribute:"plugin_publication_date", value:"2020/06/05"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios"); script_set_attribute(attribute:"stig_severity", value:"I"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_family(english:"CISCO"); script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof."); script_dependencies("cisco_ios_version.nasl"); script_require_keys("Host/Cisco/IOS/Version", "Host/Cisco/IOS/Model"); exit(0); } include('cisco_workarounds.inc'); include('ccf.inc'); get_kb_item_or_exit("Host/local_checks_enabled"); product_info = cisco::get_product_info(name:'Cisco IOS'); if ('catalyst' >!< tolower(product_info.model) || product_info.model !~ "45\d\d(^\d|$)") audit(AUDIT_HOST_NOT, 'an affected model'); if (report_paranoia < 2) audit(AUDIT_PARANOID); version_list=make_list( '15.3(3)JPJ', '15.2(4)E8', '15.2(4)E7', '15.2(4)E6', '15.2(4)E5a', '15.2(4)E5', '15.2(4)E4', '15.2(4)E3', '15.2(4)E2', '15.2(4)E1', '15.2(4)E', '15.2(3)E5', '15.2(3)E4', '15.2(3)E3', '15.2(3)E2', '15.2(3)E1', '15.2(3)E', '15.2(2b)E', '15.2(2)E9a', '15.2(2)E9', '15.2(2)E8', '15.2(2)E7b', '15.2(2)E7', '15.2(2)E6', '15.2(2)E5b', '15.2(2)E5a', '15.2(2)E5', '15.2(2)E4', '15.2(2)E3', '15.2(2)E2', '15.2(2)E10', '15.2(2)E1', '15.2(2)E', '15.2(1)E3', '15.2(1)E1', '15.2(1)E', '15.1(2)SG8', '15.1(2)SG7', '15.1(2)SG6', '15.1(2)SG5', '15.1(2)SG4', '15.1(2)SG3', '15.1(2)SG2', '15.1(2)SG1', '15.1(2)SG', '15.1(1)SG2', '15.1(1)SG1', '15.1(1)SG', '15.0(2)XO', '15.0(2)SG9', '15.0(2)SG8', '15.0(2)SG7', '15.0(2)SG6', '15.0(2)SG5', '15.0(2)SG4', '15.0(2)SG3', '15.0(2)SG2', '15.0(2)SG11', '15.0(2)SG10', '15.0(2)SG1', '15.0(2)SG', '15.0(2)EX8', '15.0(2)EX2', '15.0(1)XO1', '15.0(1)XO', '15.0(1)EY2', '15.0(1)EY', '12.2(54)WO', '12.2(54)SG1', '12.2(54)SG', '12.2(53)SG9', '12.2(53)SG8', '12.2(53)SG7', '12.2(53)SG6', '12.2(53)SG5', '12.2(53)SG4', '12.2(53)SG3', '12.2(53)SG2', '12.2(53)SG11', '12.2(53)SG10', '12.2(53)SG1', '12.2(52)SG' ); reporting = make_array( 'port' , 0, 'severity' , SECURITY_WARNING, 'version' , product_info['version'], 'bug_id' , 'CSCvk71355' ); cisco::check_and_report( product_info:product_info, reporting:reporting, vuln_versions:version_list );NASL family CISCO NASL id CISCO-SA-SNMP-DOS-USXSYTK5-IOSXE.NASL description According to its self-reported version, Cisco IOS XE Software is affected by a vulnerability in the Simple Network Management Protocol (SNMP) subsystem due to insufficient input validation when the software processes specific SNMP object identifiers. An authenticated, remote attacker can exploit this, by sending a crafted SNMP packet to an affected device, in order to cause a denial of service (DoS) condition. Please see the included Cisco BIDs and Cisco Security Advisory for more information. last seen 2020-06-12 modified 2020-06-05 plugin id 137145 published 2020-06-05 reporter This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof. source https://www.tenable.com/plugins/nessus/137145 title Cisco IOS XE Software Simple Network Management Protocol DoS (cisco-sa-snmp-dos-USxSyTk5) code #TRUSTED 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 # # (C) Tenable Network Security, Inc. # include('compat.inc'); if (description) { script_id(137145); script_version("1.6"); script_set_attribute(attribute:"plugin_modification_date", value:"2020/06/10"); script_cve_id("CVE-2020-3235"); script_xref(name:"CISCO-BUG-ID", value:"CSCvk71355"); script_xref(name:"CISCO-SA", value:"cisco-sa-snmp-dos-USxSyTk5"); script_xref(name:"IAVA", value:"2020-A-0239"); script_name(english:"Cisco IOS XE Software Simple Network Management Protocol DoS (cisco-sa-snmp-dos-USxSyTk5)"); script_set_attribute(attribute:"synopsis", value: "The remote device is missing a vendor-supplied security patch"); script_set_attribute(attribute:"description", value: "According to its self-reported version, Cisco IOS XE Software is affected by a vulnerability in the Simple Network Management Protocol (SNMP) subsystem due to insufficient input validation when the software processes specific SNMP object identifiers. An authenticated, remote attacker can exploit this, by sending a crafted SNMP packet to an affected device, in order to cause a denial of service (DoS) condition. Please see the included Cisco BIDs and Cisco Security Advisory for more information."); # https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snmp-dos-USxSyTk5 script_set_attribute(attribute:"see_also", value:"http://www.nessus.org/u?528a5571"); script_set_attribute(attribute:"see_also", value:"http://tools.cisco.com/security/center/viewErp.x?alertId=ERP-73388"); script_set_attribute(attribute:"see_also", value:"https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvk71355"); script_set_attribute(attribute:"solution", value: "Upgrade to the relevant fixed version referenced in Cisco bug ID CSCvk71355 or apply the workaround mentioned in the vendor advisory"); script_set_cvss_base_vector("CVSS2#AV:N/AC:M/Au:S/C:N/I:N/A:C"); 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:L/UI:N/S:C/C:N/I:N/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-2020-3235"); script_set_attribute(attribute:"exploitability_ease", value:"No known exploits are available"); script_cwe_id(118); script_set_attribute(attribute:"vuln_publication_date", value:"2020/06/03"); script_set_attribute(attribute:"patch_publication_date", value:"2020/06/03"); script_set_attribute(attribute:"plugin_publication_date", value:"2020/06/05"); script_set_attribute(attribute:"plugin_type", value:"local"); script_set_attribute(attribute:"cpe", value:"cpe:/o:cisco:ios_xe"); script_set_attribute(attribute:"stig_severity", value:"I"); script_end_attributes(); script_category(ACT_GATHER_INFO); script_family(english:"CISCO"); script_copyright(english:"This script is Copyright (C) 2020 and is owned by Tenable, Inc. or an Affiliate thereof."); script_dependencies("cisco_ios_xe_version.nasl"); script_require_keys("Host/Cisco/IOS-XE/Version", "Host/Cisco/IOS-XE/Model"); exit(0); } include('cisco_workarounds.inc'); include('ccf.inc'); get_kb_item_or_exit("Host/local_checks_enabled"); product_info = cisco::get_product_info(name:'Cisco IOS XE Software'); if ('catalyst' >!< tolower(product_info.model) || product_info.model !~ "45\d\d(^\d|$)") audit(AUDIT_HOST_NOT, 'an affected model'); if (report_paranoia < 2) audit(AUDIT_PARANOID); version_list=make_list( '3.9.2bE', '3.9.2E', '3.9.1E', '3.9.0E', '3.8.8E', '3.8.7E', '3.8.6E', '3.8.5aE', '3.8.5E', '3.8.4E', '3.8.3E', '3.8.2E', '3.8.1E', '3.8.0E', '3.7.3E', '3.7.2E', '3.7.1E', '3.7.0E', '3.6.9E', '3.6.8E', '3.6.7E', '3.6.6E', '3.6.5bE', '3.6.5aE', '3.6.5E', '3.6.4E', '3.6.3E', '3.6.1E', '3.6.10E', '3.6.0bE', '3.6.0E', '3.5.3E', '3.5.2E', '3.5.1E', '3.5.0E', '3.4.8SG', '3.4.7SG', '3.4.6SG', '3.4.5SG', '3.4.4SG', '3.4.3SG', '3.4.2SG', '3.4.1SG', '3.4.0SG', '3.3.2XO', '3.3.2SG', '3.3.1XO', '3.3.1SG', '3.3.0XO', '3.3.0SG', '3.2.9SG', '3.2.8SG', '3.2.7SG', '3.2.6SG', '3.2.5SG', '3.2.4SG', '3.2.3SG', '3.2.2SG', '3.2.1SG', '3.2.11SG', '3.2.10SG', '3.2.0SG', '3.10.2E', '3.10.1sE', '3.10.1aE', '3.10.1E', '3.10.0cE', '3.10.0E' ); reporting = make_array( 'port' , 0, 'severity' , SECURITY_WARNING, 'version' , product_info['version'], 'bug_id' , 'CSCvk71355' ); cisco::check_and_report( product_info:product_info, reporting:reporting, vuln_versions:version_list );