Set user agent to NUL in the --user-agent flag

[Romulo-Romero]

Hi,
I have been trying to generate a random useragent from time to time using an extension, but the -> const char kUserAgent[] = "user-agent"; switch has sanitization here:

bool HttpUtil::IsValidHeaderValue(std::string_view value) { // Just a sanity check: disallow NUL, CR and LF. for (char c : value) { if (c == '\0' || c == '\r' || c == '\n') return false; } return true;
this is from the chromium source code.

So question is, is there a way that I can add and arbitrary ascii character or some other technique to bypass this sanitazation ? or any part of the code that I can change so it would allow me to have an empty useragent in this switch which would enable my extension to generate random useragents without being detected ?

Thank you

[uazo]

So question is, is there a way that I can add and arbitrary ascii character or some other technique to bypass this sanitazation ?

I don't think so.
it is necessary to eliminate cr/lf since the presence of cr/lf would allow any header to be inserted in the http request header.

technique to bypass this sanitazation ?

would be a security bug and a big one at that.

[Romulo-Romero]

Thank you for your reply. Yeah, that makes sense, but is there a way to have an empty useragent and let only the extension do its job ? or perhaps get rid of the Platform property of the useragent?

[Romulo-Romero]

So question is, is there a way that I can add and arbitrary ascii character or some other technique to bypass this sanitazation ?

I don't think so. it is necessary to eliminate cr/lf since the presence of cr/lf would allow any header to be inserted in the http request header.

technique to bypass this sanitazation ?

would be a security bug and a big one at that.

You can make it less detectable by adding empty useragent with this flag ->>> --user-agent= (then add a randomized useragent). But for advanced detectors will flag it due to a pipe at the end | after the useragent server and client, but 99.9% of the websites dont have such detections.