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> To exploit a vulnerability in the terminal emulator, an attacker must be able to insert a carefully crafted escape sequence into the terminal stream. For a Pu
by consto 11y ago
> To exploit a vulnerability in the terminal emulator, an attacker must be able to insert a carefully crafted escape sequence into the terminal stream. For a PuTTY SSH session, this must be before encryption, so the attacker likely needs access to the server you're connecting to. For instance, an attacker on a multi-user machine that you connect to could trick you into running cat on a file they control containing a malicious escape sequence. (Unix write(1) is not a vector for this, if implemented correctly.)
From the sounds of it, an attacker needs to either compromise the machine you intend to ssh into, or mitm before you first ever connect. Once keys are cached you should easily notice if you've been mitmed.
- frozenport 11y agoYes, they need to compromise the server but they also need to compromise the client. With both compromised they will have the same execution privileges as the original Putty.exe, then they will need to ROPgadget? If they have both compromised by the heck do they need to use putty?
- Drdrdrq 11y agoNo, they must control the server, and with that they can compromise the client. Or at least this is how I understand it.
- nitrogen 11y agoAn attacker might just need to get something to show up into a log file that is then viewed using PuTTY. Always escape attacker-controlled data before logging or displaying it.
- frozenport 11y agoOkay, but crashing the client isn't the same thing as compromising the client.
- nitrogen 11y agoFrom the linked page describing the bug: > This might be exploitable if the attacker could arrange for UCSWIDE to be in memory somewhere near a sensitive data structure. Crashes are very frequently capable of being exploited, to the point that every crashing bug should be treated as a security vulnerability. At the very least, it's a DoS.
- jimrandomh 11y agoNo, it's much much worse than that. If you cat a log file, and the log file contains untrusted binary data (such as raw logging of an invalid request to a webserver or something), this can potentially exploit the vulnerability.