1 From ee45a34907ffeb5fd95b0513040d8491d565b663 Mon Sep 17 00:00:00 2001 |
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2 From: Eldar Zaitov <[email protected]> |
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3 Date: Wed, 30 Jan 2013 23:22:27 +0100 |
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4 Subject: [PATCH] Curl_sasl_create_digest_md5_message: fix buffer overflow |
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5 |
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6 When negotiating SASL DIGEST-MD5 authentication, the function |
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7 Curl_sasl_create_digest_md5_message() uses the data provided from the |
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8 server without doing the proper length checks and that data is then |
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9 appended to a local fixed-size buffer on the stack. |
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10 |
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11 This vulnerability can be exploited by someone who is in control of a |
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12 server that a libcurl based program is accessing with POP3, SMTP or |
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13 IMAP. For applications that accept user provided URLs, it is also |
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14 thinkable that a malicious user would feed an application with a URL to |
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15 a server hosting code targetting this flaw. |
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16 |
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17 Bug: http://curl.haxx.se/docs/adv_20130206.html |
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18 |
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19 (Note that these changes need to be applied to similar code in |
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20 .../lib/smtp.c for curl version 7.26.0) |
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21 |
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22 --- lib/smtp.c.orig 2013-02-05 08:06:03.823585006 -0800 |
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23 +++ lib/smtp.c 2013-02-05 08:12:38.007595100 -0800 |
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24 @@ -879,7 +879,7 @@ |
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25 char cnonce[] = "12345678"; /* will be changed */ |
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26 char method[] = "AUTHENTICATE"; |
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27 char qop[] = "auth"; |
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28 - char uri[128] = "smtp/"; |
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29 + char uri[128]; |
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30 char response[512]; |
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31 |
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32 (void)instate; /* no use for this yet */ |
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33 @@ -963,8 +963,8 @@ |
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34 for(i = 0; i < MD5_DIGEST_LEN; i++) |
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35 snprintf(&HA1_hex[2 * i], 3, "%02x", digest[i]); |
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36 |
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37 - /* Orepare URL string, append realm to the protocol */ |
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38 - strcat(uri, realm); |
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39 + /* Prepare URL string, append realm to the protocol */ |
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40 + snprintf(uri, sizeof(uri), "smtp/%s", realm); |
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41 |
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42 /* Calculate H(A2) */ |
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43 ctxt = Curl_MD5_init(Curl_DIGEST_MD5); |
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44 @@ -1008,20 +1008,11 @@ |
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45 for(i = 0; i < MD5_DIGEST_LEN; i++) |
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46 snprintf(&resp_hash_hex[2 * i], 3, "%02x", digest[i]); |
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47 |
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48 - strcpy(response, "username=\""); |
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49 - strcat(response, conn->user); |
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50 - strcat(response, "\",realm=\""); |
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51 - strcat(response, realm); |
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52 - strcat(response, "\",nonce=\""); |
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53 - strcat(response, nonce); |
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54 - strcat(response, "\",cnonce=\""); |
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55 - strcat(response, cnonce); |
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56 - strcat(response, "\",nc="); |
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57 - strcat(response, nonceCount); |
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58 - strcat(response, ",digest-uri=\""); |
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59 - strcat(response, uri); |
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60 - strcat(response, "\",response="); |
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61 - strcat(response, resp_hash_hex); |
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62 + snprintf(response, sizeof(response), |
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63 + "username=\"%s\",realm=\"%s\",nonce=\"%s\"," |
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64 + "cnonce=\"%s\",nc=\"%s\",digest-uri=\"%s\",response=%s", |
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65 + conn->user, realm, nonce, |
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66 + cnonce, nonceCount, uri, resp_hash_hex); |
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67 |
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68 /* Encode it to base64 and send it */ |
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69 result = Curl_base64_encode(data, response, 0, &rplyb64, &len); |
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