Vulnerabilities > CVE-2008-4500 - Improper Input Validation vulnerability in Solarwinds Serv-U File Server

Attack vector
Attack complexity
Privileges required
Confidentiality impact
Integrity impact
Availability impact
low complexity
exploit available


Serv-U through 7.3, including, allows remote authenticated users to cause a denial of service (CPU consumption) via a crafted stou command, probably related to MS-DOS device names, as demonstrated using "con:1".

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.


descriptionServ-U <= 7.3 (stou con:1) Denial of Service Vulnerability (auth). CVE-2008-4500. Dos exploit for windows platform
last seen2016-02-01
titleServ-U <= 7.3 stou con:1 Denial of Service Vulnerability auth


NASL familyFTP
descriptionThe installed version of Serv-U 7.x is earlier than and thus is reportedly affected by the following issues : - An authenticated, remote attacker can cause the service to consume all CPU time on the remote host by specifying a Windows port (eg,
last seen2020-06-01
plugin id34398
reporterThis script is Copyright (C) 2008-2018 Tenable Network Security, Inc.
titleServ-U 7.x < Multiple Remote Vulnerabilities (DoS, Traversal)
# (C) Tenable Network Security, Inc.


if (description)
  script_cvs_date("Date: 2018/11/15 20:50:22");

  script_cve_id("CVE-2008-4500", "CVE-2008-4501");
  script_bugtraq_id(31556, 31563);
  script_xref(name:"EDB-ID", value:"6660");
  script_xref(name:"EDB-ID", value:"6661");
  script_xref(name:"Secunia", value:"32150");

  script_name(english:"Serv-U 7.x < Multiple Remote Vulnerabilities (DoS, Traversal)");
  script_summary(english:"Checks Serv-U version");

  script_set_attribute(attribute:"synopsis", value:
"The remote FTP server is affected by several vulnerabilities.");
  script_set_attribute(attribute:"description", value:
"The installed version of Serv-U 7.x is earlier than and thus
is reportedly affected by the following issues :

  - An authenticated, remote attacker can cause the service
    to consume all CPU time on the remote host by 
    specifying a Windows port (eg, 'CON:') when using the 
    STOU command provided he has write access to a 

  - An authenticated, remote attacker can overwrite or create
    arbitrary files via a directory traversal attack in the
    RNTO command.

  - An authenticated, remote attacker may be able to upload a
    file to the current Windows directory with rename by 
    placing the destination in '\' (ie, 'My Computer').");
  script_set_attribute(attribute:"see_also", value:"");
  script_set_attribute(attribute:"see_also", value:"");
  script_set_attribute(attribute:"solution", value:"Upgrade to Serv-U version or later.");
  script_set_attribute(attribute:"exploitability_ease", value:"Exploits are available");
  script_set_attribute(attribute:"exploit_available", value:"true");
  script_cwe_id(20, 22);

  script_set_attribute(attribute:"plugin_publication_date", value:"2008/10/14");

  script_set_attribute(attribute:"plugin_type", value:"remote");
  script_set_attribute(attribute:"cpe", value:"cpe:/a:serv-u:serv-u");


  script_copyright(english:"This script is Copyright (C) 2008-2018 Tenable Network Security, Inc.");

  script_require_ports("Services/ftp", 21);



port    = get_ftp_port(default:21);
version = get_kb_item_or_exit('ftp/'+port+'/servu/version');
source  = get_kb_item_or_exit('ftp/'+port+'/servu/source');

if (version !~ "^[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+$" && version =~ "^7\.3$")
  exit(0, "The Serv-U version, "+version+" on port "+port+" is not granular enough.");

if (
  version =~ "^7\." &&
  ver_compare(ver: version , fix: '', strict: FALSE) == -1
  if (report_verbosity > 0)
    report = 
      '\n  Installed version : ' + version +
      '\n  Version source    : ' + source +
      '\n  Fixed version     :' +
    security_hole(port: port, extra: report);
  else security_hole(port);
else exit(0, "The Serv-U version "+version+" install listening on port "+port+" is not affected.");