CVE-2018-0689

HTTP header injection vulnerability in SEIKO EPSON printers and scanners (DS-570W firmware versions released prior to 2018 March 13, DS-780N firmware versions released prior to 2018 March 13, EP-10VA firmware versions released prior to 2017 September 4, EP-30VA firmware versions released prior to 2017 June 19, EP-707A firmware versions released prior to 2017 August 1, EP-708A firmware versions released prior to 2017 August 7, EP-709A firmware versions released prior to 2017 June 12, EP-777A firmware versions released prior to 2017 August 1, EP-807AB/AW/AR firmware versions released prior to 2017 August 1, EP-808AB/AW/AR firmware versions released prior to 2017 August 7, EP-879AB/AW/AR firmware versions released prior to 2017 June 12, EP-907F firmware versions released prior to 2017 August 1, EP-977A3 firmware versions released prior to 2017 August 1, EP-978A3 firmware versions released prior to 2017 August 7, EP-979A3 firmware versions released prior to 2017 June 12, EP-M570T firmware versions released prior to 2017 September 6, EW-M5071FT firmware versions released prior to 2017 November 2, EW-M660FT firmware versions released prior to 2018 April 19, EW-M770T firmware versions released prior to 2017 September 6, PF-70 firmware versions released prior to 2018 April 20, PF-71 firmware versions released prior to 2017 July 18, PF-81 firmware versions released prior to 2017 September 14, PX-048A firmware versions released prior to 2017 July 4, PX-049A firmware versions released prior to 2017 September 11, PX-437A firmware versions released prior to 2017 July 24, PX-M350F firmware versions released prior to 2018 February 23, PX-M5040F firmware versions released prior to 2017 November 20, PX-M5041F firmware versions released prior to 2017 November 20, PX-M650A firmware versions released prior to 2017 October 17, PX-M650F firmware versions released prior to 2017 October 17, PX-M680F firmware versions released prior to 2017 June 29, PX-M7050F firmware versions released prior to 2017 October 13, PX-M7050FP firmware versions released prior to 2017 October 13, PX-M7050FX firmware versions released prior to 2017 November 7, PX-M7070FX firmware versions released prior to 2017 April 27, PX-M740F firmware versions released prior to 2017 December 4, PX-M741F firmware versions released prior to 2017 December 4, PX-M780F firmware versions released prior to 2017 June 29, PX-M781F firmware versions released prior to 2017 June 27, PX-M840F firmware versions released prior to 2017 November 16, PX-M840FX firmware versions released prior to 2017 December 8, PX-M860F firmware versions released prior to 2017 October 25, PX-S05B/W firmware versions released prior to 2018 March 9, PX-S350 firmware versions released prior to 2018 February 23, PX-S5040 firmware versions released prior to 2017 November 20, PX-S7050 firmware versions released prior to 2018 February 21, PX-S7050PS firmware versions released prior to 2018 February 21, PX-S7050X firmware versions released prior to 2017 November 7, PX-S7070X firmware versions released prior to 2017 April 27, PX-S740 firmware versions released prior to 2017 December 3, PX-S840 firmware versions released prior to 2017 November 16, PX-S840X firmware versions released prior to 2017 December 8, PX-S860 firmware versions released prior to 2017 December 7) may allow a remote attackers to lead a user to a phishing site or execute an arbitrary script on the users web browser.

Weakness

The product receives data from an HTTP agent/component (e.g., web server, proxy, browser, etc.), but it does not neutralize or incorrectly neutralizes CR and LF characters before the data is included in outgoing HTTP headers.

Affected Software

Extended Description

     HTTP agents or components may include a web server, load balancer, reverse proxy, web caching proxy, application firewall, web browser, etc. Regardless of the role, they are expected to maintain coherent, consistent HTTP communication state across all components. However, including unexpected data in an HTTP header allows an attacker to specify the entirety of the HTTP message that is rendered by the client HTTP agent (e.g., web browser) or back-end HTTP agent (e.g., web server), whether the message is part of a request or a response.

When an HTTP request contains unexpected CR and LF characters, the server may respond with an output stream that is interpreted as “splitting” the stream into two different HTTP messages instead of one. CR is carriage return, also given by %0d or \r, and LF is line feed, also given by %0a or \n. In addition to CR and LF characters, other valid/RFC compliant special characters and unique character encodings can be utilized, such as HT (horizontal tab, also given by %09 or \t) and SP (space, also given as + sign or %20). These types of unvalidated and unexpected data in HTTP message headers allow an attacker to control the second “split” message to mount attacks such as server-side request forgery, cross-site scripting, and cache poisoning attacks. HTTP response splitting weaknesses may be present when:

Potential Mitigations

• Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. If an input does not strictly conform to specifications, reject it or transform it into something that conforms.
• When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
• Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/105.html
• https://cwe.mitre.org/data/definitions/31.html
• https://cwe.mitre.org/data/definitions/34.html
• https://cwe.mitre.org/data/definitions/85.html

References

• https://jvn.jp/en/jp/JVN89767228/index.html
• https://www.epson.jp/support/misc/20181203_oshirase.htm